Image decoding device

ABSTRACT

An image decoding device is equipped with a header information decoding means for decoding profile/level information included in a video parameter set after decoding byte-aligned 16-bit extension information (next_essential_info_byte_offset) in the video parameter set.

TECHNICAL FIELD

The present invention relates to an image decoding device that decodeshierarchically coded data which has been obtained by hierarchicallycoding an image.

BACKGROUND ART

An example of either information transmitted in a communication systemor information recorded in a storage device is an image or a movingimage. In the related art, in order to transmit and store the image(hereinafter, including the moving image), a technology of coding theimage has been known.

As moving image coding schemes, H.264/MPEG-4, AVC, and high-efficiencyvideo coding (HEVC) that is succeeding codec have been known (NPL 1).

In such a moving image coding scheme, images (pictures) constituting themoving image are managed, and coded/decoded by a hierarchical structurewhich is constituted by slices obtained by splitting an image, codingtree blocks (hereinafter, referred to as a CTB) obtained by splittingthe slice, and coding units obtained by recursively quad-splitting theCTB.

Further, the coding unit (hereinafter referred to as CU) is furtherappropriately split to conversion units for managing a process for atransform coefficient and prediction units for managing a process for apredicted image.

Further, in these moving image coding schemes, normally, a predictedimage is generated based on a local decoded image obtained bycoding/decoding an input image, and a prediction residual (also referredto as “a difference image” or “a residual image”) obtained bysubtracting the predicted image from the input image (an original image)is coded through orthogonal transformation and quantization.

Examples of a generation method of the predicted image described aboveinclude an inter-picture prediction (inter-prediction) and anintra-picture prediction (intra-prediction).

In the inter-prediction, the predicted image is generated by inter-framemotion compensation. In contrast, in the intra-prediction, the predictedimages of a frame are sequentially generated, based on the local decodedimage in the same frame.

Further, in HEVC, a prediction unit size of the motion compensation ininter-prediction is represented by a combination of split by CU and asplit type to be signaled for each CU.

Further, in recent years, a hierarchical coding technology forhierarchically coding an image according to a required data rate hasbeen proposed.

Examples of the hierarchical coding method include an H.264/AVC Annex GScalable Video coding (SVC) as the standard of ISO/IEC and ITU-T.

The SVC supports spatial scalability, temporal scalability, and SNRscalability. For example, in a case of the spatial scalability, first,an image obtained by down-sampling an original image to a desiredresolution is coded as a lower layer in the H.264/AVC. In addition, alower layer referred to in a target layer to be decoded is termed areference layer. Next, in the target layer, inter-layer prediction isperformed in order to remove redundancy between layers. Examples of theinter-layer prediction include motion information prediction thatpredicts information regarding the motion prediction, from informationregarding the reference layer at the same time, or texture predictionthat performs prediction from an image obtained by up-sampling a decodedimage of the reference layer at the same time (NPL 2). In the motioninformation prediction, motion information is coded, with the motioninformation (a motion vector or the like) of a reference layer as anestimation value.

Further, according to NPL 1, the following concepts are defined in orderto indicate a function or a parameter regarding a range of coded data(or hierarchically coded data) of an image that an image decoding device(decoder) can handle (can decode).

(1) “profile” defining a combination of coding tools (elementtechnology), assuming a specific application

(2) “level” defining limits of parameters (configuring information), inaccordance with the size of an image, and the like

The profile defines a set of coding tools (element technology) requiredfor decoding coded data of a coded image. Since the profile has beendefined, only a suitable profile rather than the entire specificationmay be implemented in an individual application, and there is anadvantage of being able to reduce the complexity of the decoder/encoder.

Further, the level defines the capability of a decoder and thecomplexity of a bit stream. For example, the level defines the decoder'sdecoding speed for the bit stream. Further, the level defines a range ofsupporting a tool defined in each profile. Therefore, it is necessary tosupport the lower level, in the higher level.

For example, in NPL 1, as illustrated in FIG. 28, various parameterslimited by the levels include a maximum luminance sample rate (Max lumasample rate), a maximum luminance picture size (Max luma picture size),a maximum bit rate (Max bitrate), a maximum CPB size (Max CPB size), aminimum compression ratio (Min compression Ratio), a maximum number ofslices per picture (Max slices per picture), and the like. In addition,a sub-concept of the level includes “tier” indicating whether themaximum bit rate of a bit stream (coded data) corresponding to eachlevel and the maximum CPB size for storing a bit stream are valuesdefined by a main tier (for consumer) or values defined by a high tier(for business).

For example, in NPL 1, the main profile is defined as a profile. In themain profile, for example, constraints of the coding tool illustrated inFIG. 29(a) are defined. Further, in the main profile, additional levellimits illustrated in FIG. 29(b) are defined in addition to the limitsdefined by the level illustrated in FIG. 28.

Further, in NPL 1, a profile to which a bit stream conforms isdesignated by a profile identifier general_profile_idc (SYNZ103 in FIG.30) in the profile/level information profile_tier_level( ) illustratedin FIG. 30. For example, when a bit stream conforms to the main profile,the value of the general_profile_idc is set to 1.

Further, there is general_profile_compatibility_flag[i] (SYNZ104 in FIG.30) indicating whether or not a decoder conforming to a profile otherthan the profiles designated by the profile identifiergeneral_profile_idc can decode a current bit stream. For example, if aprofile is compatible with the main profile,general-profile-compatibility-flag [1]=1 is set.

Further, whether or not a level indicating the complexity of the bitstream or the capability of a decoder required for decoding the bitstream conforms to any level of FIG. 28 is designated by a levelidentifier general_level_idc (SYNZ106 in FIG. 30) in the profile/levelinformation profile_tier_level( ). For example, when the value of thelevel identifier general_level_idc indicates “61”, it indicates that thelevel corresponds to level 6.1 in FIG. 28; and when the value of thelevel identifier general_level_idc indicates “10”, it indicates that thelevel corresponds to level 1 in FIG. 28. In other words, a tens digit(second digit) and units digit (first digit) of the value indicated bythe level identifier general_level_idc respectively correspond to theinteger and the value of the decimal point of the level in FIG. 28.

Further, the levels designated by the level identifier general_level_idcinclude a tier flag general_tier_flag (SYNZ102 in FIG. 30) indicatingwhether a tier is the main tier or the high tier. When the value of thetier flag general_tier_flag is 0, it indicates the main tier, and whenthe value is 1, it indicates the high tier.

Further, in the profile/level information profile_tier_level( )illustrated in FIG. 30, if the sublayer profile present flagsub_layer_profile_present_flag[i] (SYNZ107 in FIG. 30) and the sublayerlevel present flag sub_layer_level_present_flag[i] (SYNZ108 in FIG. 30)are both 1, the profile information (hereinafter, also referred to assublayer profile information, SYNZ111, SYNZ112, SYNZ110, SYNZ109, andSYNZ113 in FIG. 30) and the level information (hereinafter, referred toas sublayer level information, syntax SYNZ114 in FIG. 30) for each layerregarding time scalability (hereinafter, also referred to as a sublayer)can explicitly be designated.

In addition, in NPL 1, the profile/level information profile_tier_level() is signaled in both parameter sets of a video parameter set VPSillustrated in FIG. 7(a) and a sequence parameter set SPS illustrated inFIG. 7(b).

CITATION LIST Non Patent Literature

-   NPL 1: “High efficiency video coding (HEVC) text specification draft    8(JCTVC-J1003-d7)”, Joint Collaborative Team on Video coding    (JCT-VC) of ITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11 10th Meeting:    Stockholm, SE, 11-20 Jul. 2012 (published Jul. 28, 2012)-   [NPL 2] ITU-T H.264 “Advanced video coding for generic audiovisual    services” (published in November, 2007)

SUMMARY OF INVENTION Technical Problem

However, the profile/level information profile_tier_level( ) (FIG. 30)in the related art has the following problems.

(1) In a data structure of syntax regarding the profile/levelinformation profile_tier_level( ) illustrated in FIG. 30, a sublayerprofile present flag and a sublayer level present flag regarding thei-th sublayer, and sublayer profile information and sublayer levelinformation regarding the sublayer are represented per sublayer.Accordingly, in order to achieve sublayer profile information andsublayer level information regarding a specific j-th sublayer, it isnecessary to decode syntax regarding the 0-th to (j−1)-th pieces of thesublayer profile information and the sublayer level information. Inother words, there is a problem in that it is not easy to decode andextract the sublayer profile information and the sublayer levelinformation regarding any sublayer.

(2) The sublayer profile present flag and the sublayer level presentflag are both represented by one bit. Further, the sublayer profileinformation (a portion of “SYNZ201” in FIG. 30 (SYNZ109, SYNZ110,SYNZ111, SYNZ112, and SYNZ113)) is represented by a total of 56 bits (7bytes), and the sublayer level information (SYN114 in FIG. 30) isrepresented by 8 bits (1 byte). Therefore, syntax after the sublayerprofile present flag and the sublayer level present flag, in otherwords, the sublayer profile information and the sublayer levelinformation are not byte-aligned. Accordingly, since the sublayerprofile information and the sublayer level information regarding thesublayer are over a byte boundary, there is a problem in that the numberof reading/writing from the memory is increased.

(3) In the profile/level information profile_tier_level( ), when thevalue of the profile present flag ProfilePresentFlag is 0, the sublayerprofile information is not signaled, without being dependent on thevalue of the sublayer profile present flag of the sublayer. Accordingly,when the value of the profile present flag ProfilePresentFlag is 0,there is a problem in that the sublayer profile present flag of thesublayer is redundantly signaled.

(4) In the profile/level information profile_tier_level( ), the tierflag general_tier_flag related to the level information is signaled,while being dependent on the value of the profile present flagProfilePresentFlag. When the value of the ProfilePresentFlag is 0, onlythe level identifier general_level_idc is signaled, and thus there is aproblem in that it is difficult for the decoder to achieve constraintsof a level determined by the level identifier general_level_idc and thetier flag general_tier_flag. Similarly, even in the sublayer, thesublayer tier flag sub_layer_tier_flag[i] related to the sublayer levelinformation is signaled while being dependent on the values of theprofile present flag and the sublayer profile present flag. When thevalue of the profile present flag or the sublayer profile present flagis 0 and the value of the sublayer level present flag is 1, only thesublayer level identifier sub_layer_level_idc[i] is signaled, and thereis a problem in that it is difficult for the decoder to achieveconstraints of a level determined by the sublayer level identifiersub_layer_level_idc[i] and the sublayer tier flag sub_layer_tier_flag[i]regarding a certain sublayer.

As described above, from (1) and (2), in the data structure of theprofile/level information, a process regarding coding/decoding of theprofile information and the level information is complicated, and thusthe data structure is not desirable from the point of view ofimplementation of an coder/decoder. Further, from the problem of (3),the redundancy of the sublayer profile present flag causes an increasein the amount of symbols. Further, from the problem of (4), there is aproblem in that it is difficult for the decoder to achieve someparameters regarding level constraints in a specific condition.

The present invention has been made in view of the above problems, andan object thereof is to realize an image decoding device capable ofreducing a processing amount for decoding profile information and levelinformation, by improving a syntax and a data structure related to theprofile/level information required for determining whether or not adecoder can decode coded data (or hierarchically coded data) obtained bycoding an image.

Solution to Problem

In order to solve the above problems, according to an aspect of thepresent invention, there is provided an image decoding device whichdecodes hierarchically coded data obtained by hierarchically codingimage information regarding images of different qualities for respectivelayers, and restores an image of a target layer to be decoded, the imagedecoding device including profile information decoding means fordecoding profile information regarding the target layer from the codeddata, in a case where a profile present flag (ProfilePresentFlag)indicating whether or not to present profile information indicating thatthe coded data of the target layer can be decoded by an image decodingdevice including which profile indicates that the profile informationregarding the target layer is presented, and configuring profileinformation regarding a predetermined decoded layer to profileinformation regarding the target layer, in a case where the profilepresent flag indicates that profile information regarding the targetlayer is not presented, level information decoding means for decoding,from the coded data, level information indicating that the coded data ofthe target layer can be decoded by an image decoding device includingwhich level, sublayer profile present flag decoding means for decoding,from the coded data, a sublayer profile present flag(sub_layer_profile_flag) indicating whether or not to present sublayerprofile information regarding each sublayer included in the targetlayer, sublayer level present flag decoding means for decoding, from thecoded data, a sublayer level present flag (sub_layer_level_flag)indicating whether or not to present sublayer level informationregarding each sublayer included in the target layer, sublayer profileinformation decoding means for decoding the sublayer profile informationregarding each sublayer included in the target layer, in a case whereafter the decoding of the sublayer profile present flag regarding eachsublayer, the sublayer profile present flag indicates that the sublayerprofile information is presented, and configuring the profileinformation regarding the target layer to the sublayer profileinformation regarding the sublayer in a case where the sublayer profilepresent flag indicates that the sublayer profile information is notpresented, and sublayer level information decoding means for decodingthe sublayer level information regarding each sublayer included in thetarget layer, in a case where after the decoding of the sublayer levelpresent flag regarding each sublayer, the sublayer level present flagindicates that the sublayer level information is presented, andconfiguring the level information regarding the target layer to thesublayer level information regarding the sublayer in a case where thesublayer level present flag indicates that the sublayer levelinformation is not presented.

In order to solve the above problems, according to another aspect of thepresent invention, there is provided an image decoding device whichdecodes hierarchically coded data obtained by hierarchically codingimage information regarding images of different qualities for respectivelayers, and restores an image of a target layer to be decoded, the imagedecoding device including profile information decoding means fordecoding, from the coded data, profile information regarding the targetlayer, in a case where a profile level present flag(ProfileLevelPresentFlag) indicating whether or not to present theprofile information and the level information respectively indicatingthat the coded data of the target layer can be decoded by an imagedecoding device including which profile and which level indicates thatprofile information and level information regarding the target layer arepresented, and configuring profile information regarding a predetermineddecoded layer to the profile information regarding the target layer, ina case where the profile level present flag indicates that the profileinformation and the level information regarding the target layer are notpresented, level information decoding means for decoding, from the codeddata, level information regarding the target layer, in a case where theprofile level present flag indicates that the profile information andthe level information regarding the target layer are presented, andconfiguring level information regarding a predetermined decoded layer tothe level information regarding the target layer, in a case where theprofile level present flag indicates that the profile information andthe level information regarding the target layer are not presented,sublayer profile level present flag decoding means for decoding, fromthe coded data, a sublayer profile level present flag indicating whetheror not to present sublayer profile information and sublayer levelinformation regarding each sublayer included in the target layer,sublayer profile information decoding means for decoding the sublayerprofile information regarding each sublayer included in the targetlayer, in a case where the sublayer profile level present flag indicatesthat the sublayer profile information and the sublayer level informationare presented, and configuring the profile information regarding thetarget layer to the sublayer profile information regarding the sublayer,in a case where the sublayer profile level present flag indicates thatthe sublayer profile information and the sublayer level information arenot presented, and sublayer level information decoding means fordecoding the sublayer level information regarding each sublayer includedin the target layer, in a case where the sublayer profile level presentflag indicates that the sublayer profile information and the sublayerlevel information are presented, and configuring the level informationregarding the target layer to the sublayer level information regardingthe sublayer, in a case where the sublayer profile level present flagindicates that the sublayer profile information and the sublayer levelinformation are not presented.

According to another aspect of the present invention, there is providedan image decoding device which decodes coded data obtained by codingimage information, the image decoding device comprising: headerinformation decoding means for decoding header information for decodinga video parameter set included in the coded data, wherein the headerinformation decoding means decodes information for expansion in thevideo parameter set, and thereafter decodes profile/level informationincluded in the video parameter set.

Advantageous Effects of Invention

According to the aspects of the present invention, it is possible toreduce a processing amount for decoding the profile/level informationrequired for determining whether an image decoding device can decodecoded data (or hierarchically coded data) obtained by coding an image.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a functional block diagram illustrating a schematicconfiguration of a profile/level information decoding unit 1211according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a layer structure of hierarchicallycoded data according to the embodiment of the present invention, (a)illustrates hierarchically coded data on a hierarchical moving imagecoding device, and (b) illustrates hierarchically coded data on ahierarchical moving image decoding device.

FIG. 3 is a diagram illustrating a sublayer regarding time scalability.(a) is a diagram illustrating an example of a sublayer regarding timescalability, and (b) is a diagram illustrating another example of asublayer regarding time scalability.

FIG. 4 is a diagram illustrating a configuration of hierarchically codeddata according to the embodiment of the present invention, (a)illustrates a sequence layer defining a sequence SEQ, (b) illustrates apicture layer defining a picture PICT, (c) illustrates a slice layerdefining a slice S, (d) illustrates a tree block layer defining a treeblock TBLK, and (e) illustrates a CU layer defining a coding unit (CU)included in the tree block TBLK.

FIG. 5 is a functional block diagram illustrating a schematicconfiguration of a hierarchical moving image decoding device accordingto an embodiment of the present invention.

FIG. 6 is a functional block diagram illustrating a schematicconfiguration of a variable length decoding unit 12 according to anembodiment of the present invention.

FIG. 7 is a diagram illustrating an example of syntax according tohierarchically coded data. (a) is a diagram illustrating an example ofsyntax of a video parameter set VPS, (b) is a diagram illustrating anexample of syntax of a sequence parameter set SPS, and (c) is a diagramillustrating an example of syntax of an NAL unit header.

FIG. 8 is a functional block diagram illustrating a schematicconfiguration of a prediction parameter restoration unit included in thehierarchical moving image decoding device.

FIG. 9 is a functional block diagram illustrating a schematicconfiguration of a texture restoration unit included in the hierarchicalmoving image decoding device.

FIG. 10 is a functional block diagram illustrating a schematicconfiguration of a base decoding unit included in the hierarchicalmoving image decoding device.

FIG. 11 is a data structure of profile/level information according toExample 1.

FIG. 12 is a flowchart illustrating an operation of a decoding processof profile/level information in the profile/level information decodingunit 1211 according to Example 1.

FIG. 13 is a data structure of another example (Modification 1) ofprofile/level information according to Example 1.

FIG. 14 is a flowchart illustrating another example (Modification 1) ofan operation of a decoding process of profile/level information in theprofile/level information decoding unit 1211 according to Example 1.

FIG. 15 is a data structure of another example (Modification 2) ofprofile/level information according to Example 1.

FIG. 16 is a data structure of another example (Modification 2a) ofprofile/level information according to Example 1.

FIG. 17 is a data structure of another example (Modification 3) ofprofile/level information according to Example 1.

FIG. 18 is a functional block diagram illustrating another schematicconfiguration of the profile/level information decoding unit 1211according to an embodiment of the present invention (Modification 3).

FIG. 19 is a flowchart illustrating another example (Modification 3) ofan operation of a decoding process of profile/level information in theprofile/level information decoding unit 1211 according to Example 1.

FIG. 20 is a functional block diagram illustrating a schematicconfiguration of the hierarchical moving image coding device accordingto the embodiment of the present invention.

FIG. 21 is a functional block diagram illustrating a schematicconfiguration of a variable length decoding unit 22 according to theembodiment of the present invention.

FIG. 22 is a functional block diagram illustrating a schematicconfiguration of a prediction information generation unit 25 included inthe hierarchical moving image coding device.

FIG. 23 is a functional block diagram illustrating a schematicconfiguration of a texture information generation unit 24 included inthe hierarchical moving image coding device.

FIG. 24 is a functional block diagram illustrating a schematicconfiguration of a profile/level information coding unit 2211 accordingto the embodiment of the present invention.

FIG. 25 is a functional block diagram illustrating another schematicconfiguration of the profile/level information coding unit 2211according to the embodiment of the present invention (Modification 3).

FIG. 26 is a diagram illustrating configurations of a transmissiondevice equipped with the hierarchical moving image coding device and areception device equipped with the hierarchical moving image decodingdevice. (a) illustrates the transmission device equipped with thehierarchical moving image coding device, and (b) illustrates thereception device equipped with the hierarchical moving image decodingdevice.

FIG. 27 is a diagram illustrating configurations of a recording deviceequipped with the hierarchical moving image coding device and a playbackdevice equipped with the hierarchical moving image decoding device. (a)illustrates the recording device equipped with the hierarchical movingimage coding device. (b) illustrates the playback device equipped withthe hierarchical moving image decoding device.

FIG. 28 represents a limit value of each parameter regarding levelconstraints in NPL 1.

FIG. 29 (a) is an example of parameter constraints regarding a mainprofile, and (b) is an example of additional level constraints regardingthe main profile in NPL 1.

FIG. 30 is a data structure of profile/level information according toNPL 1.

FIG. 31 is a diagram illustrating another example of syntax of a videoparameter set VPS.

DESCRIPTION OF EMBODIMENTS

A hierarchical moving image decoding device 1 and a hierarchical movingimage coding device 2 according to an embodiment of the presentinvention will be described with reference to FIGS. 1 to 27.

[Overview]

The hierarchical moving image decoding device (image decoding device) 1according to the embodiment decodes coded data that has been subjectedto scalable video coding (SVC) by the hierarchical moving image codingdevice (image coding device) 2. The scalable video coding refers to acoding scheme for hierarchically coding a moving image from a lowquality to a high quality. The scalable video coding is standardized by,for example, H.264/AVC Annex G SVC. Further, the quality of the movingimage described herein broadly means the elements affecting thesubjective and objective appearance of the moving image. The quality ofa moving image includes, for example, “a resolution”, “a frame rate”,“an image quality”, and “representation accuracy of a pixel”.Accordingly, hereinafter, the meaning of a different quality of themoving image illustratively indicates that “the resolutions” and thelike are different, but is not limited thereto. For example, in the caseof the moving images which are quantized in different quantization steps(in other words, in the case of the moving image which is coded bydifferent coding noises), it may be said that the qualities of themoving images are different.

Further, the SVC may be classified into (1) spatial scalability, (2)time scalability, and (3) signal to noise ratio (SNR) scalability, interms of the type of information to be hierarchized. The spatialscalability is a technology for hierarchizing data in a resolution or animage size. The time scalability is a technology for hierarchizing datain a frame rate (the number of frames per unit time). Further, the SNRscalability is a technology for hierarchizing data in a coding noise.

Prior to the detailed description of the hierarchical moving imagecoding device 2 and the hierarchical moving image decoding device 1according to the present embodiment, first, (1) a layer structure of thehierarchically coded data to be generated by the hierarchical movingimage coding device 2 and decoded by the hierarchical moving imagedecoding device 1 will be described, and subsequently, (2) a detailedexample of a data structure that can be employed in each layer will bedescribed.

[Layer Structure of Hierarchically Coded Data]

Here, a description of coding and decoding of the hierarchically codeddata using FIG. 2 is as follows. FIG. 2 is a diagram schematicallyillustrating a case of hierarchically coding/decoding a moving imageinto three hierarchies moving image of a lower hierarchy L3, a middlehierarchy L2, and a higher hierarchy L1. In other words, in the examplesillustrated in FIGS. 2(a) and (b), among three hierarchies, the higherhierarchy L1 is a highest layer, and the lower hierarchy L3 is a lowestlayer.

In the following description, a decoded image corresponding to aspecific quality which is obtained by decoding the hierarchically codeddata is referred to as a decoded image of a specific hierarchy (or adecoded image corresponding to a specific hierarchy) (for example, adecoded image POUT#A of the higher hierarchy L1).

FIG. 2(a) illustrates hierarchical moving image coding devices 2#A to2#C that generate coded data DATA#A to DATA#C by hierarchically codingrespective input images PIN#A to PIN#C. FIG. 2(b) illustrateshierarchical moving image decoding devices 1#A to 1#C that generatedecoded images POUT#A to POUT#C by decoding respective pieces of codeddata DATA#A to DATA#C which are hierarchically coded.

First, a description will be given of the coding devices with referenceto FIG. 2(a). The input images PIN#A, PIN#B, and PIN#C which are inputsof the coding devices have the same original image, but have differentimage qualities (resolution, frame rate, image quality, and the like).The image quality is lowered in the order of the input images PIN#A,PIN#B, and PIN#C.

The hierarchical moving image coding device 2#C of the lower hierarchyL3 generates the coded data DATA#C of the lower hierarchy L3 by codingthe input image PIN#C of the lower hierarchy L3. The coded data DATA#Cincludes basic information required for decoding the decoded imagePOUT#C of the lower hierarchy L3 (denoted by “C” in FIG. 2). Since thelower hierarchy L3 is a lowest hierarchy, the coded data DATA#C of thelower hierarchy L3 is referred to as basic coded data.

Further, the hierarchical moving image coding device 2#B of the middlehierarchy L2 generates coded data DATA#B of the middle hierarchy L2 bycoding the input image PIN#B of the middle hierarchy L2 while referringto the coded data DATA#C of the lower hierarchy. The coded data DATA#Bof the middle hierarchy L2 includes additional information (denoted by“B” in FIG. 2) required for decoding the decoded image POUT#B of themiddle hierarchy, in addition to the basic information “C” included inthe coded data DATA#C.

Further, the hierarchical moving image coding device 2#A of the higherhierarchy L1 generates coded data DATA#A of the higher hierarchy L1 bycoding the input image PIN#A of the higher hierarchy L1 while referringto the coded data DATA#B of the middle hierarchy L2. The coded dataDATA#A of the higher hierarchy L1 includes additional information(denoted by “A” in FIG. 2) required for decoding the decoded imagePOUT#A of the higher hierarchy, in addition to the basic information “C”required for decoding the decoded image POUT#C of the lower hierarchyL3, and the additional information “B” required for decoding the decodedimage POUT#B of the middle hierarchy L2.

In this manner, the coded data DATA#A of the higher hierarchy L1includes information regarding the decoded image of a plurality ofdifferent qualities.

Next, a description will be given of the decoding devices with referenceto FIG. 2(b). On the decoding device side, the decoding devices 1#A,1#B, and 1#C respectively corresponding to the higher hierarchy L1, themiddle hierarchy L2, and the lower hierarchy L3 respectively decode thecoded data DATA#A, DATA#B, and DATA#C so as to output the decoded imagesPOUT#A, POUT#B, and POUT#C.

In addition, some pieces of information regarding hierarchically codeddata of the higher hierarchy are extracted and a specific decodingdevice of the lower hierarchy decodes the extracted information, therebyallowing a moving image of a specific quality to be played.

For example, the hierarchical moving image decoding device 1#B of themiddle hierarchy L2 may extract information (in other words, “B” and “C”included in the hierarchically coded data DATA#A) required for decodingthe decoded image POUT#B, among the hierarchically coded data DATA#A ofthe higher hierarchy L1, and decode the decoded image POUT#B. In otherwords, the decoding devices can decode the decoded images POUT#A,POUT#B, and POUT#C, based on the information included in thehierarchically coded data DATA#A of the higher hierarchy L1.

In addition, hierarchically coded data is not limited to thehierarchically coded data of the above three hierarchies, and thehierarchically coded data may be hierarchically coded into twohierarchies, and hierarchically coded into hierarchies of the numbergreater than three hierarchies.

Further, a part or all of the coded data regarding the decoded image ofthe specific hierarchy is coded independently of the other hierarchies,during decoding of a specific hierarchy, the hierarchically coded datamay be configured to be completed without referring to otherhierarchical information. For example, in the example described abovewith reference to FIGS. 2(a) and (b), the decoding of the decoded imagePOUT#B has been described with reference to “C” and “B”, but is notlimited thereto. It is possible to configure the hierarchically codeddata such that the decoded image POUT#B can be decoded by using only“B”.

In addition, in a case of realizing the SNR scalability, after the sameoriginal image is used as the input images PIN#A, PIN#B, and PIN#C, itis possible to generate hierarchically coded data such that the decodedimages POUT#A, POUT#B, and POUT#C have different image qualities. Inthis case, the hierarchical moving image coding device of the lowerhierarchy generates hierarchically coded data by quantizing a predictionresidual by using a larger quantization width, compared to thehierarchical moving image coding device of the higher hierarchy.

In this specification, for convenience of explanation, terms are definedas follows. The following terms are used to represent the followingtechnical matters, unless otherwise indicated.

Upper layer: A hierarchy which is located higher than a certainhierarchy is referred to as a higher layer. For example, in FIG. 2, thehigher layer of the lower hierarchy L3 is the middle hierarchy L2 andthe higher hierarchy L1. Further, the decoded image of the higher layerrefers to a decoded image of a higher quality (for example, a resolutionis high, a frame rate is high, an image quality is high, and the like).

Lower layer: A hierarchy which is located lower than a certain hierarchyrefers to a lower layer. For example, in FIG. 2, the lower layer of thehigher hierarchy L1 is the middle hierarchy L2 and the lower hierarchyL3. Further, the decoded image of the lower layer refers to a decodedimage of a lower quality.

Target layer: A hierarchy which is a decoding target or coding isreferred to as a target layer.

Reference layer: A certain lower layer to be referred for decoding adecoded image corresponding to the target layer is referred to as areference layer.

In the example illustrated in FIGS. 2(a) and (b), the reference layer ofthe higher hierarchy L1 is the middle hierarchy L2 and the lowerhierarchy L3. However, without being limited thereto, it is possible toconfigure the hierarchically coded data such that all lower layers maynot be referred for decoding a certain layer. For example, thehierarchically coded data may be configured such that the referencelayer of the higher hierarchy L1 is one of the middle hierarchy L2 andthe lower hierarchy L3.

Base layer: A hierarchy which is located in the lowest layer is referredto as a base layer. The decoded image of the base layer is a decodedimage which is obtained by decoding the coded data and has the lowestquality, and is referred to as a base decoded image. In other words, thebase decoded image is a decoded image corresponding to a hierarchy ofthe lowest layer. Some pieces of coded data of the hierarchically codeddata required for decoding the basic decoded image is referred to asbasic coded data. For example, basic information “C” included in thehierarchically coded data DATA#A of the higher hierarchy L1 is basiccoded data.

Enhancement layer: the higher layer of the base layer is referred to asan enhancement layer.

Layer identifier: A layer identifier is intended to identify ahierarchy, and has a one-to-one correspondence with the hierarchy. Thehierarchically coded data includes a hierarchical identifier used forselecting partially coded data required for decoding the decoded imageof a specific hierarchy. The subset of the hierarchically coded dataassociated with the layer identifier corresponding to the specific layeris referred to as layer representation.

In general, the layer representation of the hierarchy and/or the layerrepresentation corresponding to the lower layer of the hierarchy areused for decoding of the decoded image of the specific hierarchy. Inother words, the layer representation of the target layer and/or thelayer representation of one or more hierarchies included in the lowerlayer of the target hierarchy are used for decoding of the decoded imageof the target layer.

Inter-layer prediction: Inter-layer prediction means predicting a syntaxelement value of a target layer, coding parameter used for decoding thetarget layer, and the like based on the syntax element value included inthe layer representation of a hierarchy (reference layer) different fromthe layer representation of the target layer, a value derived from thesyntax element value, and a decoded image. The inter-layer predictionfor predicting the information regarding motion prediction frominformation regarding a reference layer (at the same time) may bereferred to as motion information prediction. Further, the inter-layerprediction for performing prediction from an image obtained byup-sampling the decoded image of the lower layer (at the same time) maybe referred to as texture prediction (or inter-layer intra-prediction).In addition, the hierarchy used for the inter-layer prediction isexemplarily a lower layer of the target layer. Further, the predictionperformed in the target layer without using the reference layer may bereferred to as intra-layer prediction.

Temporal identifier: a temporal identifier is an identifier foridentifying a layer regarding time scalability (hereinafter, asublayer). The temporal identifier is for identifying the sublayer, andcorresponds to the sublayer one-to-one. The coded data includes atemporal identifier used to select partially coded data necessary fordecoding of the decoded image of a specific sublayer.

Sublayer: a sublayer is a layer regarding a time scalability specifiedby the temporal identifier. The layer is referred to as a sublayer (alsoreferred to as a temporal layer) in order to distinguish the timescalability from other scalability such as a partial scalability and SNRscalability.

In addition, hereinafter, the time scalability is realized by sublayersincluded in the coded data of the base layer or the hierarchically codeddata required for decoding a certain layer.

The time scalability will be described with reference to FIG. 3(a). Inthe SVC and the HEVC, in order to realize the time scalability, ahierarchical B picture has been introduced in which pictures of a Bpicture are referred to in a nested manner. FIG. 3(a) illustrates apicture reference relationship of the hierarchical B picture. Here, asymbol L#N indicates a certain layer N, and a symbol SL#M indicates asublayer (subhierarchy) M of time scalability belonging to a certainlayer N. In a case of realizing the time scalability by changing a framerate, the coded data of the B picture which is not referred to in otherpictures is first discarded. In the case of FIG. 3(a), the coded data ofthe sublayers SL#1 to SL#3 having a frame rate of ½ is generated bydiscarding the coded data of the B pictures (B2, B4, B6, and B8)belonging to sublayer SL#4. Further, the coded data of the sublayersSL#1 and SL#2 having a frame rate of ¼ is generated by discarding thecoded data of the B pictures (B3, and B7) belonging to sublayer SL#3, inthe B picture (FIG. 3(a)) which is not referred to from other pictures.It is possible to adjust the frame rate in a stepwise manner byrepeating the above process. Further, there is a temporal identifier(also referred to as a temporalId; tId, temporal_id) as an identifierfor identifying each sublayer. Although FIG. 3(a) is an example ofassociating the number of stages of a reference structure of each Bpicture with the sublayer one-to-one, it is not limited thereto. Forexample, the number of stages of the reference structures of a pluralityof B pictures may be associated with the sublayer one-to-one ormultiple-to-one. For example, in FIG. 3(b), the sublayer SL#1 may beassociated so as to be constituted by pictures I1, B3, B5, B7, and P9,and the sublayer SL#2 may be associated so as to be constituted bypictures B2, B4, B6, and B8.

In addition, the above terms are defined for only convenience ofexplanation, and the technical matters may be represented by differentterms.

[Data Structure of Hierarchically Coded Data]

Hereinafter, a case of using HEVC and the expansion method as a codingscheme of generating coded data of respective hierarchy will bedescribed. However, without being limited thereto, the coded data ofrespective hierarchies may be generated by a coding scheme such asMPEG-2 and H.264/AVC.

Further, the lower layer and the higher layer may be coded by differentcoding schemes. Further, the coded data of respective hierarchies may besupplied to the hierarchical moving image decoding device 1 throughtransmission paths different from each other, or may be supplied to thehierarchical moving image decoding device 1 through the sametransmission path.

For example, in a case of performing scalable coding on ahigh-resolution video (a moving image, 4K video data) in the base layerand one enhancement layer, and transmitting the video; in the baselayer, the 4K video data is down-scaled, an interlaced video data iscoded by the MPEG-2 or H.264/AVC and transmitted over a televisionbroadcasting network; and in the enhancement layer, the 4K video(progressive) is coded by the HEVC, and may be transmitted over theInternet.

(Base Layer)

FIG. 4 is a diagram illustrating a data structure of the coded data (inthe example of FIG. 2, the hierarchically coded data DATA#C) that may beemployed in the base layer. The hierarchically coded data DATA#C forexample includes a sequence, and a plurality of pictures constitutingthe sequence.

FIG. 4 illustrates a hierarchical structure of data of thehierarchically coded data DATA#C. (a) to (e) of FIG. 4 are diagramsrespectively illustrating (a) a sequence layer defining a sequence SEQ,(b) a picture layer defining a picture PICT, (c) a slice layer defininga slice S, (d) a tree block layer defining a tree block TBLK, and (e) aCU layer defining a coding unit (CU) included in the tree block TBLK.

(Sequence Layer)

In the sequence layer, a set of data that is referred to by thehierarchical moving image decoding device 1 in order to decode asequence to be processed SEQ (hereinafter, also referred to as a targetsequence) is defined. The sequence SEQ, as shown in (a) of FIG. 4,includes a video parameter set VPS, a sequence parameter set SPS,picture parameter set PPS, adaptation parameter set APS, pictures PICT₁to PICT_(NP) (NP is the total number of pictures included in thesequence SEQ), and supplemental enhancement information SEI.

In the video parameter set VPS, a set of common coding parameters to bereferred to by the hierarchical moving image decoding apparatus 1 fordecoding the target sequence is defined in the base layer and theenhancement layer. The details of the VPS will be described later.

In the sequence parameter set SPS, a set of coding parameters which arereferred to by the hierarchical moving image decoding device 1 fordecoding the target sequence is defined.

In the picture parameter set PPS, a set of coding parameters which arereferred to by the hierarchical moving image decoding device 1 fordecoding each picture in the target sequence is defined. In addition, aplurality of PPSs may exist. In this case, one of the plurality of PPSsis selected from each picture in the target sequence.

In the adaptation parameter set APS, a set of coding parameters whichare referred to by the hierarchical moving image decoding device 1 fordecoding each slice in the target sequence is defined. A plurality ofAPSs may exist. In this case, one of the plurality of APSs is selectedfrom each slice in the target sequence.

(Picture Layer)

In the picture layer, a set of data which is referred to by thehierarchical moving image decoding device 1 for decoding a picture PICTto be processed (hereinafter, also referred to as a target picture) isdefined. The picture PICT, as shown in (b) of FIG. 4, includes a pictureheader PH, and slices Si to SNS (NS is the total number of slicesincluded in the picture PICT).

In addition, hereinafter, when there is no need to distinguishrespective slices Si to SNS, they may be described by omittingsubscripts of symbols. Further, the same applies to other data, denotedby subscripts, which is included in the hierarchically coded data DATA#Cthat will be described below.

The picture header PH includes a coding parameter group which isreferred to by the hierarchical moving image decoding device 1 fordetermining a target picture decoding method. In addition, the codingparameter group does not necessarily need to be included in the pictureheader PH, and the coding parameter group may be indirectly included inthe picture header PH by referring to, for example, the pictureparameter set PPS.

(Slice Layer)

In the slice layer, a set of data which is referred to by thehierarchical moving image decoding device 1 for decoding the slice S tobe processed (also referred to as a target slice) is defined. The sliceS includes, as illustrated in (c) of FIG. 4, a slice header SH, and asequence of tree blocks TBLK₁ to TBLK_(NC) (NC is the total number oftree blocks included in the slice S).

The slice header SH includes a coding parameter group which is referredto by the hierarchical moving image decoding device 1 for determining atarget slice decoding method. Slice type designation information(slice-type) for designating a slice type is an example of codingparameters included in the slice header SH.

Examples of the slice type that can be designated by the slice typedesignation information include (1) an I slice using onlyintra-prediction in the case of coding, (2) a P slice usingunidirectional prediction or intra-prediction in the case of coding, and(3) a B slice using unidirectional prediction, bidirectional prediction,or intra-prediction in the case of coding.

In addition, the slice header SH may include reference to the pictureparameter set PPS (pic_parameter_set_id), and reference to theadaptation parameter set APS (aps_id) which are included in the sequencelayer.

Further, the slice header SH includes filter parameters FP which arereferred to by an adaptation filter included in the hierarchical movingimage decoding device 1. The filter parameter FP includes a filtercoefficient group. The filter coefficient group includes (1)number-of-taps designation information designating the number of taps ofa filter, (2) filter coefficients a₀ to a_(NT−1) (NT is the total numberof filter coefficients included in the filter coefficient group), and(3) offset.

(Tree Block Layer)

In the tree block layer, a set of data which is referred to by thehierarchical moving image decoding device 1 for decoding the tree blockTBLK to be processed (hereinafter, also referred to as a target treeblock) is defined. In addition, the tree block may be referred to as acoding tree block (CTB) or largest cording unit (LCU).

The tree block TBLK includes a tree block header TBLKH, and coding unitinformation CU₁ to CU_(NL) (NL is the total number of coding unitinformation pieces included in the tree block TBLK). Here, first, adescription of a relationship between the tree block TBLK and the codingunit information CU is as follows.

The tree block TBLK is split into partitions for specifying a block sizefor intra-prediction or inter-prediction, and each process forconversion.

The partition of the tree block TBLK is split by quad-tree recursivesplitting. The tree structure obtained by the quad-tree recursivesplitting is referred to as, hereinafter, a coding tree.

Hereinafter, a partition corresponding to a leaf which is a node of aterminal of the coding tree is referred to as a coding node. Further,since the coding node is a basic unit of a coding process, hereinafter,the coding node is also referred to as a coding unit (CU). In addition,the coding node is also referred to as a coding block (CB).

In other words, the coding unit information (hereinafter, also referredto as CU information) CU₁ to CU_(NL) is information corresponding toeach coding node (coding unit) obtained by recursivelyquad-tree-splitting the tree block TBLK.

Further, the root of the coding tree is associated with the tree blockTBLK. In other words, the tree block TBLK is associated with the highestnode of the tree structure of the quad-tree splitting recursivelyincluding a plurality of coding nodes.

In addition, the size of each coding node is half of the horizontal andvertical sizes of a coding node to which the coding node directlybelongs (in other words, the partition of a node which is one hierarchyhigher than the coding node).

Further, the size of the tree block TBLK and the size of each codingnode depend on size designation information regarding a minimum codingnode and the difference in hierarchy depths of the maximum coding nodeand the minimum coding node, which are included in the sequenceparameter set SPS of the hierarchically coded data DATA#C. For example,when the size of the minimum coding node is 8×8 pixels and thedifference in hierarchy depths of the maximum coding node and theminimum coding node is 3, the size of the tree block TBLK is 64×64pixels, and one of four types of sizes, in other words, 64×64 pixels,32×32 pixels, 16×16 pixels, and 8×8 pixels, may be used as the size ofthe coding node.

(Tree Block Header)

The tree block header TBLKH includes coding parameters which arereferred to by the hierarchical moving image decoding device 1 fordetermining a target tree block decoding method. Specifically, as shownin (d) of FIG. 4, the tree block header includes tree block splitinformation SP_TBLK designating a split pattern of the target tree blockinto each CU, and quantization parameter difference Δqp(qp−delta)designating the size of a quantization step.

The tree block split information SP_TBLK is information indicating acoding tree for splitting the tree block, specifically, informationdesignating the shape and size of each CU included in the target treeblock, and the position of the CU in the target tree block.

Further, the quantization parameter difference Δqp is a differenceqp−qp′ between the quantization parameter qp of the target tree blockand the quantization parameter qp′ in the coded tree block immediatelybefore the target tree block.

(CU Layer)

In the CU layer, a set of data which is referred to by the hierarchicalmoving image decoding device 1 for decoding the CU to be processed(hereinafter, referred to as an object CU) is defined.

Here, prior to the description of the specific contents of data includedin the CU information CU, a tree structure of data included in the CUwill be described. The coding node is a root node of a prediction tree(PT) and a transform tree (TT). The descriptions of the prediction treeand the transform tree are as follows.

In the prediction tree, the coding node is split into one or a pluralityof prediction blocks, and the position and the size of each predictionblock are defined. In other words, the prediction block is one or aplurality of regions, which do not overlap with each other, constitutingthe coding node. Further, the prediction tree includes one or aplurality of prediction blocks which are obtained by the above division.

The prediction process is performed for each prediction block.Hereinafter, a prediction block which is a unit of prediction is alsoreferred to as a prediction unit (PU).

Further, in the transform tree, the coding node is split into the one ora plurality of transform blocks, and the position and size of eachtransform block is defined. In other words, a transform block is one ora plurality of regions constituting the coding node, which do notoverlap with each other. Further, the transform tree includes one or aplurality of transform blocks which are obtained from the abovesplitting.

The transform process is performed for each transform block.Hereinafter, a transform block which is a unit of transform is referredto as a transform unit (TU).

(Data Structure of CU Information)

Subsequently, the specific contents of data included in the CUinformation CU will be described with reference to FIG. 4(e). Asillustrated in FIG. 4(e), the CU information CU includes, specifically,a skip flag SKIP, prediction tree information (hereinafter, abbreviatedas PT information) PTI, and transform tree information (hereinafter,abbreviated as TT information) TTI.

(Skip Flag)

The skip flag SKIP is a flag indicating whether or not the skip mode isapplied to the target PU. When the value of the skip flag SKIP is 1, inother words, when the skip mode is applied to the target CU, some piecesof PT information PTI and TT information TTI in the CU information CUare omitted. In addition, the skip flag SKIP is omitted in the I slice.

[PT Information]

The PT information PTI is information regarding the prediction tree(hereinafter, abbreviated as PT) included in the CU. In other words, thePT information PTI is a set of information regarding each of one or aplurality of PUs included in the PT, and is referred when a predictedimage is generated by the hierarchical moving image decoding device 1.As illustrated in FIG. 4(e), the PT information PTI includes predictiontype information PType and prediction information PInfo.

The prediction type information PType is information designating whetheran intra-prediction is used or an inter-prediction is used as apredicted image generation method for the target PU.

The prediction information PInfo includes intra-prediction informationPP-Intra or inter-prediction information PP-Inter, depending on whichprediction method is designated by the prediction type informationPtype. Hereinafter, a PU to which the intra-prediction is applied isreferred to as an intra-PU, and a PU to which the inter-prediction isapplied is referred to as an inter-PU.

The inter-prediction information PP-Inter includes coding parameterswhich are referred to by the hierarchical moving image decoding device 1when generating an inter-predicted image by the inter-prediction. Morespecifically, the inter-prediction information PP-Inter includesinter-PU split information designating a split pattern of the target CUto each inter-PU, and inter-prediction parameter for each inter-PU.Examples of the inter-prediction parameter include an estimated motionvector index (mvp_idx), a reference image index (ref_idx), aninter-prediction flag (inter_pred_flag), and a motion vector residual(mvd).

The intra-prediction information PP-Intra includes coding parameterswhich are referred to by the hierarchical moving image decoding device 1when generating an intra-predicted image by the intra-prediction. Morespecifically, the intra-prediction information PP-Intra includesintra-PU split information designating a split pattern of the target CUto each intra-PU, and intra-prediction parameter for each intra-PU. Theintra-prediction parameter is a parameter for designating anintra-prediction method (prediction mode) for each intra-PU. Examples ofintra-prediction parameter include an estimated prediction mode flag, anestimated prediction mode index, and a residual prediction mode index.

Further, the PU split information may include information designatingthe shape, size, and position of the target PU. Assuming that the sizeof the target CU is 2N×2N pixels, the PU split type designated by the PUsplit information have a total of eight types of patterns as follows. Inother words, they are four types of symmetric splittings such as 2N×2Npixels, 2N×N pixels, N×2N pixels, and N×N pixels, and four types ofasymmetric splitting such as 2N×nU pixels, 2N×nD pixels, nL×2N pixels,and nR×2N pixels. In addition, it means that N=2^(m) (m is an arbitraryinteger of 1 or more). Hereinafter, a region obtained by splitting thetarget CU is also referred to as a partition.

[TT Information]

TT information TTI is information regarding a transform tree(hereinafter, abbreviated as TT) included in the CU. In other words, theTT information TTI is a set of information regarding one or each of aplurality of TUs included in the TT, and is referred during the decodingof the residual data by the hierarchical moving image decoding device 1.In addition, hereinafter, the TU is referred to as a block.

As illustrated in FIG. 4(e), the TT information TTI includes TT splitinformation SP_TT for designating a splitting pattern of the target CUto each transform block, and quantized prediction residuals QD₁ toQD_(NT) (NT is a total number of blocks included in the target CU).

Specifically, the TT split information SP_TT is information fordetermining the shape and size of each TU included in the target CU, andthe position of each TU in the target CU. For example, it is possible torealize the TT split information SP_TT from the information(split_transform_unit_flag) indicating whether or not to performsplitting of a node which is a target and the information (trafoDepth)indicating the depth of the splitting.

Further, for example, when the size of CU is 64×64, each TU obtained bysplitting has a size of 32×32 pixels to 4×4 pixels.

Each quantized prediction residual QD is coded data generated by thehierarchical moving image coding device 2 performing the followingprocesses 1 to 3 on the target block which is a processing target block.

Process 1: Frequency conversion (for example, discrete cosine transform(DCT) and discrete sine transform (DST)) of a prediction residualobtained by subtracting a predicted image from a coding target image;

Process 2: Quantization of transform coefficients obtained by theprocess 1;

Process 3: Variable-length coding of the transform coefficientsquantized in the process 2;

In addition, the quantization parameter qp described above representsthe size of the quantization step QP used when the hierarchical movingimage coding device 2 quantizes the transform coefficients(QP=2^(qp/6)).

(Enhancement Layer)

It is possible to employ, for example, a data structure similar to thedata structure shown in FIG. 4, for the coded data of the enhancementlayer. However, in the coded data of the enhancement layer, it ispossible to add additional information or to omit a parameter asfollows.

Information indicating hierarchical coding may be coded in the VPS orthe SPS.

Further, respective pieces of hierarchical identification informationregarding the spatial scalability, the time scalability, and the SNRscalability (respectively, dependency_id, temporal_id, and quality_id)may be coded in the slice layer. It is possible to code filterinformation and on/off information regarding a filter (described later)by the PPS, the slice header, the macro block header, and the like.

Further, a skip flag (skip_flag), a base mode flag (base_mode_flag) anda prediction mode flag (pred_mode_flag) may be coded in the CUinformation CU.

Further, the flags may specify that the CU type of the target CU is anyof the intra-CU, the inter-CU, the skip CU and the base skip CU.

It is possible to define the intra-CU and the skip CU similar to thecase of the HEVC method described above. For example, in the skip CU,“1” is set in the skip flag. In the case of not skip CU, “0” is set inthe skip flag. Further, in the intra-CU, “0” is set in the predictionmode flag.

Further, the inter-CU may be defined as a CU to which a non-skip ormotion compensation (MC) is applied. In the inter-CU, for example, “0”is set in the skip flag, and “1” is set in the prediction mode flag.

The base skip CU is a CU type of estimating the information regardingthe CU or the PU from the reference layer. Further, in the base skip CU,for example, “1” is set in the skip flag, “1” is set in the base modeflag.

Further, the PT information PTI may specify that the PU type of thetarget PU is any of the intra-PU, the inter-PU, the merge PU, and thebase merge PU.

It is possible to define the intra-PU, the inter-PU, and the merge PU,similar to the case of the HEVC method described above.

In addition, it is possible to use a configuration of omitting themotion vector information which can be derived from the motion vectorinformation included in the lower layer among motion vector informationincluded in the enhancement layer from the enhancement layer. By such aconfiguration, it is possible to reduce the code amount of theenhancement layer, and thus the coding efficiency is improved.

Further, the coded data of the enhancement layer may be generated by thecoding scheme different from the coding scheme of the lower layer, asdescribed above. In other words, the coding and decoding process of theenhancement layer is not dependent on the type of the codec of the lowerlayer.

The lower layer may be coded by, for example, the MPEG-2 or theH.264/AVC method.

When the target layer and the reference layer are coded by differentcoding schemes, it is possible to maintain compatibility of each otherin the inter-layer by transforming the parameter of the reference layerinto a corresponding parameter or a similar parameter of the targetlayer. For example, it is possible to read and interpret the macro blockof the MPEG-2 or the H.264/AVC method as the CTB of the HEVC.

In addition, the parameters described above may be coded alone, and aplurality of parameters may be coded in a complex manner. When theplurality of parameters are coded in a complex manner, an index isassigned to the combination of the parameter values, and the assignedindex is coded. Further, if the parameters can be derived from anotherparameter and decoding information, it is possible to omit coding of theparameters.

[Hierarchical Moving Image Decoding Device]

Hereinafter, the configuration of the hierarchical moving image decodingdevice 1 according to the present example will be described withreference to FIGS. 1 to 19.

(Configuration of Hierarchical Moving Image Decoding Device)

The description of a schematic configuration of the hierarchical movingimage decoding device 1 with reference to FIG. 5 is as follows. FIG. 5is a functional block diagram illustrating a schematic configuration ofthe hierarchical moving image decoding device 1. The hierarchical movingimage decoding device 1 generates a decoded image POUT#T of a targetlayer by decoding the hierarchically coded data DATA supplied from thehierarchical moving image coding device 2 by an HEVC method.

As illustrated in FIG. 5, the hierarchical moving image decoding device1 includes an NAL demultiplexing unit 11, a variable length decodingunit 12, a prediction parameter restoration unit 14, a texturerestoration unit 15, and a base decoding unit 16.

[NAL Demultiplexing Unit 11]

The NAL demultiplexing unit 11 demultiplexes the hierarchically codeddata DATA which is transmitted in an NAL unit in a network abstractionlayer (NAL).

The NAL is a layer provided in order to abstract the communicationbetween a video coding layer (VCL) and a lower system that transmits andstores the coded data.

The VCL is a layer for performing a moving image coding process, andcoding is performed by the VCL. Meanwhile, the lower system referred toherein corresponds to the file formats of H.264/AVC and HEVC, and anMPEG-2 system. In the example illustrated below, the lower systemcorresponds to the decoding process in the target layer and referencelayer.

In addition, in the NAL, a bit stream generated by the VCL is separatedinto an NAL unit, and transmitted to the lower system which is adestination. The NAL unit includes coded data which has been coded bythe VCL, and a header (NAL unit header: nal_unit_header( )) for thecoded data to appropriately reach the lower system which is thedestination. In addition, the NAL unit header may be represented by thesyntax shown in, for example, FIG. 7(c). The NAL unit header includes an“nal_unit_type” representing a type of coded data stored in the NALunit, “nuh_temporal_id plus1” representing an identifier (temporalidentifier) of a sublayer to which the stored coded data belongs, and“nuh_layer_id” (or nuh_reserved_zero_6bits) representing an identifierof a layer (layer identifier) to which the stored coded data belongs.

Further, the coded data in each hierarchy is stored in an NAL unit, suchthat the coded data is NAL multiplexed and transmitted to thehierarchical moving image decoding device 1.

The NAL demultiplexing unit 11 extracts target layer coded data DATA#Tand reference layer coded data DATA#R (hereinafter, simply referred toas coded data DATA#R) by demultiplexing the hierarchically coded dataDATA. Further, the NAL demultiplexing unit 11 supplies the target layercoded data DATA#T (hereinafter, simply referred to as coded data DATA#T)to the variable length decoding unit 12, and supplies the referencelayer coded data DATA#R to the base decoding unit 16.

[Variable Length Decoding Unit 12]

The variable length decoding unit 12 performs a decoding process ofinformation for decoding various syntax values from binary valuesincluded in the target layer coded data DATA#T.

Specifically, the variable length decoding unit 12 includes, asillustrated in FIG. 6, a header information decoding unit 121, aprediction information decoding unit 122, and a transform coefficientinformation decoding unit 123. Further, the header information decodingunit 121 includes a profile/level information decoding unit 1211.

[Header Information Decoding Unit 121]

The header information decoding unit 121 decodes the header informationregarding parameters used for decoding, per sequence, per picture, orper slice, from the coded data DATA#T.

The header information decoding unit 121 decodes information used fordecoding per sequence, based on syntax definition defining a VPS and anSPS included in the coded data DATA#T.

For example, from the VPS, the syntax shown in FIG. 7(a) is decoded.Each syntax has a meaning as follows. In addition, the syntax shown inFIG. 7(a) is an example of the syntax of the VPS, and the syntaxincludes set HRD parameters of parameters (hrd-parameters) for operatinga virtual decoder so as to satisfy the capabilities of a decoder (sizesof a CPB and a DPB, and the like) defined by level information(including sublayer level information) determined for each layer whichis not shown in FIG. 7(a), the enhancement flags of the VPS, theenhancement data of the VPS, and the like.

-   -   “video_parameter_set_id” is an identifier for identifying each        VPS.    -   “vps_temporal_id_nesting_flag” is a flag indicating whether to        additionally constrain inter-prediction of a picture referring        to the VPS.    -   “vps_reserved_zero_2bits” is syntax that is reserved when        expanding the future HEVC.    -   “vps_reserved_zero_6bits”, or “vps_max_num_layers_minus1” is        syntax used to calculate an upper limit MaxNumLayers of the        number of layers for the other scalabilities, other than the        time scalability, with respect to the hierarchically coded data        including at least the base layer. In addition, the upper limit        MaxNumLayers of the number of layers is represented by        MaxNumLayers=vps_max_num_layers_minus1+1. When the        hierarchically coded data is constituted only by the base layer,        it is established that vps_max_num_layers_minus1=0.    -   “vps_max_sub_layer_minus1” is syntax that is used to calculate        an upper limit MaxNumSubLayers of the number of layers        (sublayers) regarding the time scalability of the hierarchically        coded data including at least the base layer. In addition, the        upper limit MaxNumSubLayers of the number of sublayers is        represented by MaxNumSubLayers=vps_max_sub_layers_minus1+1.    -   “profile_tier_level(X,Y)” is syntax (hereinafter, also referred        to as profile/level information) indicating the profile        information and the level information regarding the        hierarchically coded data. In addition, an argument X is the        value of the profile information present flag        ProfilePresentFlag, and an argument Y is a value of (the upper        limit of the number of sublayers−1), that is,        MaxNumSubLayersMinus1. In addition, the argument Y may be the        value of the MaxNumSubLayers, instead of the value of (the upper        limit of the number of sublayers−1) MaxNumSubLayersMinus1. In        this case, the MaxNumSubLayersMinus1 of the profile/level        information profile_tier_level( ) is interpreted as        “MaxNumSubLayers−1”. Hereinafter, a description will be made by        using the upper limit of the number of sublayers        MaxNumSubLayers, instead of the value of (the upper limit of the        number of sublayers−1) MaxNumSubLayersMinus1. In addition, the        profile/level information profile_tier_level( ) will be        described later. In addition, in the profile/level information        defined herein, the maximum of the profile/level information        required for the decoder to decode all layers (including the        base layer, the enhancement layer, and sublayers associated with        each layer) is set.

In addition, the profile/level information profile_tier_level( )included in the VPS is decoded in the profile/level information decodingunit 1211 described later.

-   -   “vps_reserved_zero_12bits” or “next_essential_info_byte_offset”        is an offset value indicating the number of bytes from the first        position of the NAL unit including the VPS to the next important        syntax represented by a fixed length symbol on the VPS.

Further, from the SPS, for example, the syntax illustrated in FIG. 7(b)is decoded. The meaning of each syntax is as follows. In addition, thesyntax illustrated in FIG. 7(b) is an example of syntax of the SPS, andincludes information regarding the image size which is not illustratedin FIG. 7(b), information regarding a crop, an enhancement flag of theSPS, enhancement data of the SPS, and the like.

-   -   “video_parameter_set” is a VPS identifier        (video_parameter_set_id) for specifying a VPS to be referenced        by the SPS corresponding to the SPS identifier        (seq_parameter_set_id) described later.    -   “sps_max_sub_layers_minus1” is syntax used to calculate an upper        limit MaxNumSubLayers of the number of sublayers regarding the        time scalability of the target layer. In addition, the upper        limit MaxNumSubLayers of the number of sublayers is represented        by MaxNumSubLayers=sps_max_sub_layers_minus1+1.    -   “sps_reserved_zero_bit” is syntax reserved when expanding a        future HEVC.    -   “profile_tier_level(X,Y)” is syntax representing the profile        information and the level information regarding the coded data        of the target layer DATA#T. In addition, an argument X is the        value of the profile information present flag        ProfilePresentFlag, and an argument Y is the value of (the upper        limit of the number of sublayers−1), in other words,        MaxNumSubLayersMinus1. In addition, in the profile/level        information defined in the SPS, the profile/level information        required for the decoder to decode the target layer and the        sublayer associated with the target layer is set. In addition,        the profile/level information profile_tier_level( ) included in        the SPS is decoded in the profile/level information decoding        unit 1211 described later.    -   “seq_parameter_set_id” is an identifier for identifying each        SPS.

The header information decoding unit 121 further includes aprofile/level information decoding unit 1211 that decodes profile/levelinformation profile_tier_level( ) included in the VPS and the SPS. Theprofile/level information decoding unit 1211 decodes the profile/levelinformation profile_tier_level( ) from the coded data DATA#T, with theprofile present flag ProfilePresentFlag and the number of sublayersMaxNumSubLayers as inputs. The details will be described later.

In addition, with respect to the syntax placed at the beginning on theVPS, as illustrated in FIG. 31, the syntax“next_essensial_info_byte_offset” (“vps_reserved_zero_12bits”) denotedby a symbol SYNL101 is placed immediately before the profile/levelinformation profile_tier_level( ) and thus each syntax may bedecoded/coded in the following order.

-   -   video_parameter_set_id    -   vps_temporal_id_nesting_flag    -   vps_reserved_zero_2bits    -   vps_reserved_zero_6bits    -   vps_max_sub_layers_minus1    -   next_essensial_info_byte_offset    -   profile_tier_level(ProfilePresentFlag,        vps_max_sub_layers_minus1)    -   . . . following omitted . . . .

Since the syntax “next_essensial_info_byte_offset” is placed immediatelybefore the profile/level information on the VPS, even if the entireprofile/level information on the VPS is not decoded, there is an effectin that it is possible to directly and early access and decode importantinformation located in the byte offset position designated by“next_essential_info_byte_offset”. Further, in order to keep the bytealignment of the first syntax of the VPS, it is preferable to change thecode length of the syntax “next_essensial_info_byte_offset” from 12 bitsto 16 bits. Further, it is possible to expand the byte offset that canbe designated, by expanding the code length of the syntax“next_essensial_info_byte_offset” to 16 bits.

[Prediction information decoding unit 122] The prediction informationdecoding unit 122 decodes prediction information regarding each CU or PUfrom the coded data DATA#T.

The prediction information includes, for example, informationdesignating a CU type or a PU type and information for specifying theshape, size, and position of the CU.

When the CU is the inter-CU, the prediction information decoding unit122 decodes PU split information from the coded data DATA#T. Inaddition, in each PU, the prediction information decoding unit 122further decodes a reference image index (refIdx), motion informationsuch as an estimated motion vector index (mvp_idx), and a motion vectorresidual (mvd), and mode information, as the prediction information,from the coded data DATA#T.

Meanwhile, when the CU is an intra-CU, the prediction informationdecoding unit 122 decodes (1) size designation information fordesignating a size of a prediction unit and (2) prediction indexdesignation information for designating a prediction index, asprediction information, from coded data DATA#T.

Further, the prediction information decoding unit 122 decodes tree blocksplit information for designating a split pattern of the target treeblock to each CU, in other words, information for designating the shape,the size, and the position in the target tree block of each CU includedin the target tree block (information for specifying the shape, thesize, and the position of the CU) from coded data DATA#T.

Further, the prediction information decoding unit 122 supplies thedecoded prediction information to the prediction parameter restorationunit 14.

[Transform Coefficient Information Decoding Unit 123]

The transform coefficient information decoding unit 123 decodes thequantization prediction residual QD regarding each block and aquantization parameter difference Δqp regarding a tree block includingthe block, from the coded data DATA#T. The transform coefficientinformation decoding unit 123 supplies the quantization predictionresidual QD and the quantization parameter difference Δqp which aredecoded, as the transform coefficient information, to the texturerestoration unit 15.

[Base Decoding Unit 16]

The base decoding unit 16 decodes base decoding information which isinformation regarding a reference layer which is referred to whendecoding the decoded image corresponding the target layer, from thereference layer coded data DATA#R. The base decoding informationincludes a base prediction parameter, a base transform coefficient, anda base decoded image. The base decoding unit 16 supplies the decodedbase decoding information to the prediction parameter restoration unit14 and the texture restoration unit 15.

[Prediction Parameter Restoration Unit 14]

The prediction parameter restoration unit 14 restores a predictionparameter by using prediction information and base decoding information.The prediction parameter restoration unit 14 supplies the restoredprediction parameter to the texture restoration unit 15. In addition,when restoring the prediction parameter, the prediction parameterrestoration unit 14 can refer to the inter-prediction parameter which isstored in the frame memory 155 (described later) included in the texturerestoration unit 15.

[Texture Restoration Unit 15]

The texture restoration unit 15 generates a decoded image POUT#T byusing the transform coefficient information, the base decodinginformation, and the prediction parameter, and outputs the decoded imagePOUT#T to the outside. In addition, in the texture restoration unit 15,information regarding the restored decoded image is stored in a framememory 155 (described later) provided therein.

Hereinafter, a description will be made regarding respective details ofthe base decoding unit 16, the prediction parameter restoration unit 14,and the texture restoration unit 15.

(Prediction Parameter Restoration Unit)

The detailed configuration of the prediction parameter restoration unit14 will be described with reference to FIG. 8. FIG. 8 is a functionalblock diagram illustrating a configuration of the prediction parameterrestoration unit 14.

As illustrated in FIG. 8, the prediction parameter restoration unit 14includes a prediction type selection unit 141, a switch 142, anintra-prediction parameter restoration unit 143, and an inter-predictionparameter restoration unit 145.

The prediction type selection unit 141 controls the derivation processof the prediction parameter by sending a switching instruction to theswitch 142 depending on the CU type or the PU type. The details are asfollows.

When the intra-CU or the intra-PU is designated, the prediction typeselection unit 141 controls the switch 142 so as for theintra-prediction parameter restoration unit 143 to derive the predictionparameter.

When the inter-CU and the inter-PU are designated, the prediction typeselection unit 141 controls the switch 142 so as for theinter-prediction parameter restoration unit 145 to derive the predictionparameter.

The switch 142 supplies the prediction information to either of theintra-prediction parameter restoration unit 143 or the inter-predictionparameter restoration unit 145, in response to the instruction from theprediction type selection unit 141. The prediction parameter is derivedin the supply destination of the prediction information.

The intra-prediction parameter restoration unit 143 derives a predictionmode from the base decoding information or the prediction information.In other words, the intra-prediction parameter restoration unit 143restores the prediction mode (intra-prediction mode) as the predictionparameter.

In addition, the intra-prediction mode includes “Intra-Planar (planarprediction mode, a flat prediction mode)”, “Intra DC (intra DCprediction mode)”, “Intra Angular (direction prediction)”, “Intra FromLuma” for predicting color difference based on the prediction ofluminance, and the like.

When the target CU (PU) is the inter-CU (inter-PU), the inter-predictionparameter restoration unit 145 restores an inter-prediction parameterfrom the prediction information, the base decoding information, and thedecoded inter-prediction parameter which is stored in a frame memory.More specifically, the inter-prediction parameter restoration unit 145first derives estimated motion vector candidates by an intra-layermotion estimation process or an inter-layer motion estimation process,by using the base decoding information. Subsequently, theinter-prediction parameter restoration unit 145 acquires a motion vectorresidual (mvd), an estimated motion vector index (mvp_idx), aninter-prediction flag (inter_pred_flag) and a reference image index(refIdx). Then, based on the value of the inter-prediction flag,reference image list available flags are respectively determined for thereference image list L0 and the reference image list L1. Subsequently,when the corresponding reference image list available flag indicatesthat the reference image is used, the inter-prediction parameterrestoration unit 145 derives the estimated motion vector, based on thevalue of the estimated motion vector index, and derives the motionvector, based on the motion vector residual and the estimated motionvector. The inter-prediction parameter restoration unit 145 outputs theinter-prediction parameter, by combining the derived motion vectors, thereference image list available flag and the reference image index.

(Texture Restoration Unit)

The detailed configuration of the texture restoration unit 15 will bedescribed with reference to FIG. 9. FIG. 9 is a functional block diagramillustrating a configuration of the texture restoration unit 15.

As illustrated in FIG. 9, the texture restoration unit 15 includes aninverse orthogonal transform and inverse quantization unit 151, atexture prediction unit 152, an adder 153, a loop filter unit 154, and aframe memory 155.

The inverse orthogonal transform and inverse quantization unit 151, (1)inverse quantizes the quantized prediction residual QD included in thetransform coefficient information supplied from the variable lengthdecoding unit 12, (2) inverse orthogonal transforms the DCT coefficientobtained by the inverse quantization (for example, discrete cosinetransform (DCT) transform), and (3) supplies prediction residual Dobtained by the inverse orthogonal transform to the adder 153. Inaddition, when the quantized prediction residual QD is inversequantized, the inverse orthogonal transform and inverse quantizationunit 151 derives a quantization step QP from the quantization parameterdifference Δqp included in the transform coefficient information. Thequantization parameter qp can be derived by adding the quantizationparameter difference Δqp to the quantization parameter qp′ regarding thetree block which is inverse quantized/inverse orthogonal transformedimmediately before, and the quantization step QP can be derived byQP=2^(qp/6) from the quantization parameter qp. Further, the generationof the prediction residual D by the inverse orthogonal transform andinverse quantization unit 151 is performed with the block (transformunit) as a unit.

The texture prediction unit 152 generates a predicted image, withreference to the base decoded image included in the base decodinginformation or the decoded image, for which decoding has been completed,stored in the frame memory, according to the prediction parameter.

More specifically, the texture prediction unit 152 includes aninter-prediction unit 152A, an intra-layer intra-prediction unit 152B,and an inter-layer intra-prediction unit 152C.

The inter-prediction unit 152A generates a predicted image regardingeach inter-prediction partition by the inter-prediction. Specifically,the inter-prediction unit 152A generates the predicted image from thereference image, by using the motion information supplied from themotion information restoration unit 145 or the merge informationrestoration unit 147, as the prediction parameter.

The intra-layer intra-prediction unit 152B generates the predicted imageregarding each intra-prediction partition by the intra-layerintra-prediction. Specifically, the intra-layer intra-prediction unit152B generates the predicted image from the decoded image for whichdecoding has been completed, by using the prediction mode supplied fromthe intra-prediction mode restoration unit 143, as the predictionparameter.

The inter-layer intra-prediction unit 152C generates a predicted imageregarding each intra-prediction partition by the inter-layerintra-prediction. Specifically, the inter-layer intra-prediction unit152C generates a predicted image based on the base decoded imageincluded in the base decoding information, by using the prediction modesupplied from the intra-prediction mode restoration unit 143, as theprediction parameter. The base decoded image may be appropriatelyup-sampled in accordance with the resolution of the target layer.

The texture prediction unit 152 supplies the predicted images which aregenerated by the inter-prediction unit 152A, the intra-layerintra-prediction unit 152B, or the inter-layer intra-prediction unit152C, to the adder 153.

The adder 153 generates a decoded image by adding the texture predictionunit 152 predicted image and the prediction residual D supplied from theinverse orthogonal transform and inverse quantization unit 151.

The loop filter unit 154 performs a de-blocking process and a filterprocess by an adaptive filter parameter on the decoded image suppliedfrom the adder 153.

The frame memory 155 stores the decoded image which is filtered by theloop filter unit 154.

(Base Decoding Unit)

The detailed configuration of the base decoding unit 16 will bedescribed with reference to FIG. 10. FIG. 10 is a functional blockdiagram illustrating a configuration of the base decoding unit 16.

As illustrated in FIG. 10, the base decoding unit 16 includes a variablelength decoding unit 161, a base prediction parameter restoration unit162, a base transform coefficient restoration unit 163, and a basetexture restoration unit 164.

The variable length decoding unit 161 performs a decoding process ofinformation for decoding various syntax values from binary data includedin the reference layer coded data DATA#R.

Specifically, the variable length decoding unit 161 decodes theprediction information and the transform coefficient information fromthe coded data DATA#R. Since the syntaxes of the prediction informationand the transform coefficient which are decoded by the variable lengthdecoding unit 161 are the same as in the variable length decoding unit12, the detailed description thereof will be omitted.

The length decoding unit 161 supplies the decoded prediction informationto the base prediction parameter restoration unit 162, and supplies thedecoded transform coefficient information to the base transformcoefficient restoration unit 163.

The base prediction parameter restoration unit 162 restores the baseprediction parameter, based on the prediction information supplied fromthe variable length decoding unit 161. A method by which the baseprediction parameter restoration unit 162 restores the base predictionparameter is similar to the prediction parameter restoration unit 14,and thus the detailed description thereof will be omitted here. The baseprediction parameter restoration unit 162 supplies the restored baseprediction parameter to the base texture restoration unit 164, andoutputs the restored base prediction parameter to the outside.

The base transform coefficient restoration unit 163 restores thetransform coefficient, based on the transform coefficient informationsupplied from the variable length decoding unit 161. A method by whichthe base transform coefficient restoration unit 163 restores thetransform coefficient is similar to the inverse orthogonal transform andinverse quantization unit 151, and thus the detailed description thereofwill be omitted here. The base transform coefficient restoration unit163 supplies the restored base transform coefficient to the base texturerestoration unit 164, and outputs the restored base transformcoefficient to the outside.

The base texture restoration unit 164 generates a decoded image, byusing the base prediction parameter supplied from the base predictionparameter restoration unit 162 and the base transform coefficientsupplied from the base transform coefficient restoration unit 163.Specifically, the base texture restoration unit 164 generates apredicted image by performing the same texture prediction as that by thetexture prediction unit 152, based on the base prediction parameter.Further, the base texture restoration unit 164 generates the predictionresidual based on the base transform coefficient, and generates the basedecoded image by adding the generated prediction residual and thepredicted image generated by the texture prediction.

In addition, the base texture restoration unit 164 may perform the samefilter process as that by the loop filter unit 154 on the base decodedimage. Further, the base texture restoration unit 164 may include aframe memory for storing the decoded base decoded image, and may referthe decoded base decoded image which is stored in the frame memory forthe texture prediction.

Example 1 Details of Profile/Level Information Decoding Unit 1211

Next, the details of a profile/level information decoding unit 1211according to an example 1 will be described with reference to FIG. 1,FIG. 11, and FIG. 12.

FIG. 1 is a block diagram illustrating a configuration of theprofile/level information decoding unit 1211.

As illustrated in FIG. 1, the profile/level information decoding unit1211 includes a profile information decoding unit 1221 a, a levelinformation decoding unit 1221 b, a sublayer profile present flagdecoding unit 1221 c, a sublayer level present flag decoding unit 1221d, and a byte-aligned data decoding unit 1221 e.

[Profile Information Decoding Unit 1221 a]

The profile information decoding unit 1221 a decodes and outputs theprofile information regarding the target layer from the coded dataDATA#T, based on the profile present flag ProfilePresentFlag.Specifically, when the profile present flag ProfilePresentFlag is 1, theprofile information regarding the target layer is decoded from the codeddata DATA#T. When the profile present flag ProfilePresentFlag is 0, itis determined that the profile information is the same as the decodedVPS, or the profile information regarding the lower layer (for example,base layer), and the decoded VPS, or the profile information regardingthe lower layer is output as the profile information regarding thetarget layer. In addition, in the VPS which is referred to in aplurality of layers and the SPS of the base layer, the profileinformation is necessarily signaled on the coding side.

Further, the profile information decoding unit 1221 a decodes andoutputs sublayer profile information regarding each sublayer included inthe target layer from the coded data DATA#T, based on the profilepresent flag ProfilePresentFlag, the number of sublayersMaxNumSubLayers, and the sublayer profile present flagsub_layer_profile_present_flag[i] which is supplied from the sublayerprofile present flag decoding unit 1221 c. Specifically, when theprofile present flag is 1, and the sublayer profile present flag of thesublayer i (temporalId=i+1) is 1, it is determined that the decodedprofile information and the sublayer profile information are different,and the sublayer profile information regarding the sublayer i is decodedfrom the coded data DATA#T. Otherwise, it is determined that thesublayer profile information regarding the sublayer i and the decodedprofile information regarding the target layer are different, and thedecoded profile information regarding the target layer is output as thesublayer profile information.

[Level Information Decoding Unit 1221 b]

The level information decoding unit 1221 b decodes and outputs the levelinformation regarding the target layer from the coded data DATA#T.Further, the level information decoding unit 1221 b decodes and outputssublayer level information regarding each sublayer included in thetarget layer from the coded data DATA#T, based on the number ofsublayers MaxNumSubLayers, and the sublayer level present flagsub_layer_level_present_flag[i] which is supplied from the sublayerlevel present flag decoding unit 1221 d. Specifically, when the sublayerlevel present flag sub_layer_level_present_flag[i] is 1, it isdetermined that the sublayer level information regarding the sublayer i(temporalId=i+1) is different from the decoded level informationregarding the target layer, and the sublayer level information regardingthe sublayer i is decoded from the coded data DATA#T and output.Otherwise (when the sublayer level present flagsub_layer_level_present_flag[i] is 0), it is determined that the decodedlevel information regarding the target layer and the sublayer levelinformation regarding the sublayer i are the same, and the decoded levelinformation regarding the target layer is output as the sublayer levelinformation regarding the sublayer i.

[Sublayer Profile Present Flag Decoding Unit 1221 c]

The sublayer profile present flag decoding unit 1221 c decodes thesublayer profile present flag of the sublayer included in the targetlayer from the coded data DATA#T, based on the number of sublayersMaxNumSubLayers, and outputs it to the profile information decoding unit1221 a and the outside.

[Sublayer Level Present Flag Decoding Unit 1221 d]

The sublayer level present flag decoding unit 1221 d decodes thesublayer level present flag of each sublayer included in the targetlayer from the coded data DATA#T, based on the number of sublayersMaxNumSubLayers, and outputs it to the level information decoding unit1221 b and the outside.

[Byte-Aligned Data Decoding Unit 1221 e]

The byte-aligned data decoding unit 1221 e reads (decodes) thebyte-aligned data alignment_bit per bit, until the current position (perbit) on the coded data is a byte boundary, in other words, a bit locatedin the next position of the current position on the coded data is afirst bit of a byte (a bit to be first read).

(Flow of Decoding Process of Profile/Level InformationProfile_Tier_Level( ))

FIG. 11 illustrates a data structure of syntax of profile/levelinformation profile_tier_level( ) to be decoded in the profile/levelinformation decoding unit 1211, and FIG. 12 is a flowchart illustratinga decoding process of the profile/level information profile_tier_level() illustrated in FIG. 11. Hereinafter, the operation of theprofile/level information decoding unit 1211 will be described. Inaddition, in FIG. 11, as compared to FIG. 30, portions for which syntaxor statement is added or deleted are respectively indicated by a shadedline or a strike-through line. The same is applied to FIGS. 15, 16, and17.

(Step SA101)

The profile information decoding unit 1221 a determines whether or notthe profile present flag ProfilePresentFlag is 1. When the profilepresent flag ProfilePresentFlag is 1 (Yes in step SA101), the processproceeds to step SA102, or in other cases (No in step SA101), theprocess proceeds to step SA103.

(Step SA102)

The profile information decoding unit 1221 a decodes the syntax shown inFIG. 11,

-   -   profile space general_profile_space    -   tier flag general_tier_flag    -   profile identifier general_profile_idc    -   profile capability flag general_profile_compatibility_flag[i],        and    -   profile reserved syntax general_reserved_zero_16bits, from the        coded data DATA#T, and outputs it as profile information        regarding a target layer.

(Step SA103)

The profile information decoding unit 1221 a determines that the profileinformation regarding a target layer is the same as the VPS or theprofile information regarding a lower layer (for example, a base layer),and outputs the VPS or the profile information regarding the lower layerwhich is configured to the profile information regarding a target layer.

(Step SA104)

The level information decoding unit 1221 decodes the syntax shown inFIG. 11,

-   -   level identifier general_level_idc, from the coded data DATA#T,        and outputs it as level information regarding a target layer.

(Step SA105)

A loop regarding decoding of a sublayer profile present flag and asublayer level present flag of a sublayer is started. Before startingthe loop, a variable i is initialized to 0. The process of the loop isexecuted when the variable i is less than the number of sublayers−1“MaxNumSubLayers−1”, and every time the process of the loop is executed,the variable i is incremented by “1”.

(Step SA106)

The sublayer profile present flag decoding unit 1221 c decodes andoutputs a sublayer profile present flagsub_layer_profile_present_flag[i] regarding the sublayer designated bythe variable i, from the coded data DATA#T.

The sublayer level present flag decoding unit 1221 d decodes and outputsa sublayer level present flag sub_layer_level_present_flag[i] regardingthe sublayer designated by the variable i, from the coded data DATA#T.

(Step SA107)

The loop regarding the decoding of the sublayer profile present flag andthe sublayer level present flag of the sublayer is ended.

(Step SA108)

The byte-aligned data decoding unit 1221 e decodes the byte-aligned datafrom the coded data, and moves the decoding start point to a decodingstart point (a first bit) of the next syntax. More specifically, untilthe current position (per bit) on the coded data is a byte boundary, inother words, a bit located in the next position of the current positionon the coded data is a first bit of a byte (a bit to be read first), thebyte-aligned data alignment_bit is read per bit from the coded data. Inaddition, the value of the alignment_bit is 0 or 1, but it is desirableto set the value to one value.

A pseudo-code A is represented as follows. Here, a functionbyte_aligned( ) is a process of determining whether or not the currentposition (per bit) on the coded data is the byte boundary, and when thecurrent position on the coded data is the byte boundary, it isdetermined as “true”, and otherwise, it is determined as “false”.Further, a function read_bits (N) is a process of reading bit strings ofthe number of bits that are designated by an argument N, from the codeddata.

== pseudo-code A start================================================== while ( !byte_aligned ( ) ) {  read_bits ( 1 ) } ==pseudo-code A end=================================== =============

In addition, an offset from the current position on the coded data tothe decoding start point of the syntax to be decoded next is obtainedthrough calculation, without actually reading, and the position may bemoved by the number of bits indicated by the offset. The offset isobtained by the following equation.offset=8−(2*(MaxNumSubLayers−1)% 8)Specifically, in step SA105 to step SA107, since the symbol amounts ofthe sublayer profile present flag and the sublayer level present flagwhich are decoded for each sublayer are each one bit and total two bits,and the number of sublayers is MaxNumSubLayers, the sum of the symbolamounts which are decoded in step SA105 to step SA107 is2*(MaxNumSubLayers−1). Accordingly, the offset is determined by“8−(residual obtained by dividing the sum of the symbol amounts by 8)”.

(Step SA109)

A loop regarding decoding of the sublayer profile information and thesublayer level information regarding the sublayer is started. Beforestarting the loop, a variable i is initialized to 0. The process of theloop is executed when the variable i is less than the number ofsublayers−1 “MaxNumSubLayers−1”, and every time the process of the loopis executed, the variable i is incremented by “1”.

(Step SA110)

The profile information decoding unit 1221 a determines whether theprofile present flag ProfilePresentFlag and the sublayer profile presentflag of the sublayer designated by the variable isub_layer_profile_present_flag[i] are both 1. When the profile presentflag and the sublayer profile present flag are both 1 (Yes in stepSA110), the process proceeds to step SA111, or in other cases (No instep SA110), the process proceeds to step SA112.

(Step SA111)

The profile information decoding unit 1221 a decodes and outputs

-   -   sublayer profile space sub_layer_profile_space[i]    -   sublayer tier flag sub_layer_tier_flag[i]    -   sublayer profile identifier sub_layer_profile_idc[i]    -   sublayer profile capability flag        sub_layer_profile_compatibility_flag[i][j]    -   sublayer profile reserved syntax        sub_layer_reserved_zero_16bits[i],

as the sublayer profile information regarding the sublayer designated bythe variable i, from the coded data DATA#T.

(Step SA112)

The profile information decoding unit 1221 a determines that thesublayer profile information regarding the sublayer i is the same as theprofile information regarding a target layer, and outputs the sublayerprofile information which is configured to the profile informationregarding a target layer.

(Step SA113)

The level information decoding unit 1221 b determines that the sublayerlevel present flag sub_layer_level_present_flag[i] of the sublayerdesignated by the variable i is 1. When the sublayer level present flagis 1 (Yes in step SA113), the process proceeds to step SA114, or inother cases (No in step SA113), the process proceeds to step SA115.

(Step SA114)

The level information decoding unit 1221 b decodes and outputs

-   -   sublayer level identifier sub_layer_level_idc[i],

as the sublayer level information regarding the sublayer which isdesignated by the variable i, from the coded data DATA#T.

(Step S115)

The level information decoding unit 1221 b determines that the sublayerlevel information regarding the sublayer i is the same as the levelinformation regarding the target layer, and outputs the sublayer levelinformation which is configured to the level information regarding thetarget layer.

(Step SA116)

The loop regarding the decoding of the sublayer profile information andthe sublayer level information regarding the sublayer is ended.

Hitherto, the operation of the profile/level information decoding unit1211 according to Example 1 has been described, but the operation is notlimited to the steps, and the steps may be changed in a feasible range.

Further, the data structure of the profile/level information shown inFIG. 11 has the following features.

A syntax portion denoted by a symbol SYNA102 shown in FIG. 11 in otherwords, the sublayer profile present flag and the sublayer level presentflag corresponding to each sublayer, and a syntax portion denoted by asymbol SYNA103 shown in FIG. 11, in other words, the sublayer profileinformation and the sublayer level information corresponding to eachsublayer are separately signaled, and data for byte alignment(byte-aligned data) is inserted therebetween. Accordingly, all of asyntax portion denoted by a symbol SYNA101, the syntax portion denotedby the symbol SYNA102, and the syntax portion denoted by the symbolSYNA103, which are shown in FIG. 11, are byte-aligned.

Accordingly, as compared to the related art, it is possible to reducethe number of times of memory access regarding reading/writing whendecoding/coding the sublayer profile present flag, the sublayer levelpresent flag, the sublayer profile information, and the sublayer levelinformation. There is an effect of reducing a processing amount requiredfor decoding/coding the profile/level information.

Further, it is possible to calculate a offset per byte byte_offset fromthe position denoted by the symbol SYNA104 in FIG. 11 up to the decodingstart point of the sublayer profile information and the sublayer levelinformation regarding the specific sublayer X (the syntax portiondenoted by the symbol SYN103 in FIG. 11), based on a value of thesublayer profile present flag, a symbol amount (7 bytes (54 bits)) ofthe sublayer profile information, a value of the sublayer level presentflag, and a symbol amount (1 byte (8 bits)) of the sublayer profileinformation, by the next pseudo-code B. In addition, instead of theoffset per byte, the offset per bit may be calculated.

== pseudo-code B start ==========================================================  byte_offset = 0  for (i = 0; i<X; i++) {byte_offset = byte_offset + (sub_layer_profile_present_flag [i] * 7 +sub_layers_level_present_flag [i] * 1) } == pseudo-code B end================================== ======================

Accordingly, without decoding the sublayer profile information/sublayerprofile information regarding the previous sublayer of the sublayer X,it is possible to easily specify the decoding start point of thesublayer profile information/sublayer profile information regarding thesublayer X through calculation, and easily extract the sublayer profileinformation/sublayer level information regarding only the specificsublayer X. In other words, there is an effect of reducing a processingamount required for decoding the sublayer profile information/sublayerlevel information.

Further, at a time when the profile information and the levelinformation regarding a target layer are decoded, if it is determinedthat the decoder is capable of decoding the coded data of a targetlayer, it is obvious that the coded data of each sublayer can be decodedwithout decoding the profile information/level information regardingeach sublayer belonging to the target layer. Accordingly, in the case ofthe configuration, since the symbol amount of the profileinformation/level information regarding the sublayer can be easilyspecified, it is possible to omit the decoding of the profileinformation/level information regarding the sublayer.

<<Modification 1 of Profile/Level Information Decoding Unit 1211>>

Next, Modification 1 of the profile/level information decoding unit 1211according to Example 1 will be described with reference to FIG. 13 andFIG. 14.

Since a profile/level information decoding unit 1211′ according toModification 1 has the same configuration as in FIG. 1, the descriptionwill be omitted.

FIG. 13 illustrates a data structure of the syntax of profile/levelinformation profile_tier_level( ) which is decoded by the profile/levelinformation decoding unit 1211′, and FIG. 14 is a flowchart illustratinga decoding process of the syntax illustrated in FIG. 13. The differencein the data structures of the profile/level information illustrated inFIG. 13 according to Modification 1 and the profile/level informationillustrated in FIG. 11 according to Example 1 is as follows.

-   -   As illustrated in portions respectively denoted by symbols        SYNA201 and SYNA202 in FIG. 13, the sublayer profile present        flag and the sublayer level present flag are separately        signaled.    -   As illustrated in a portion denoted by a symbol SYNA201 in FIG.        13, only when the profile present flag is 1, the sublayer        profile present flag is signaled.    -   As illustrated in portions denoted by the symbols SYNA201 and        SYNA202 in FIG. 13, the byte-aligned data is inserted        respectively after the sublayer profile present flag and the        sublayer level present.

Accordingly, as compared to the related art, in Modification 1, when theprofile present flag ProfilePresentFlag is 0, since the sublayer profilepresent flag of the sublayer is not signaled, it is possible to solvethe problem in that the sublayer profile present flag of the sublayer isredundantly signaled. In other words, there is an effect of reducing theredundancy (symbol amount) of the profile/level information.

Further, similar to Example 1, since all of the profile/levelinformation is byte-aligned in Modification 1, it is possible to reducethe number of times of memory access regarding reading/writing whendecoding/coding the sublayer profile present flag, the sublayer levelpresent flag, the sublayer profile information, and the sublayer levelinformation. There is an effect of reducing a processing amount requiredfor decoding/coding the profile/level information.

Further, similar to Example 1, it is possible to easily extract thesublayer profile information/sublayer level information regarding onlythe specific sublayer X also in Modification 1. In other words, there isan effect of reducing a processing amount required for decoding thesublayer profile information/sublayer level information.

Hereinafter, the operation of the profile/level information decodingunit 1211′ according to Modification 1 will be described with referenceto FIG. 14. In addition, since the decoding process of the profileinformation/level information is similar to the steps SA101 to SA104 ofFIG. 12, the description thereof will be omitted. Further, since thedecoding process of the sublayer profile information/sublayer levelinformation is similar to the step SA108 to step SA116 of FIG. 12, thedescription thereof will be omitted.

(Step SA121)

The sublayer profile present flag decoding unit 1221 c determineswhether the profile present flag is 1. When the profile present flag is1 (Yes in step SA121), the process of step SA122 to SA125 is performed.In other cases (No in step SA121), the process proceeds to step SA126.

(Step SA122)

A loop regarding decoding of a sublayer profile present flag of asublayer is started. Before starting the loop, a variable i isinitialized to 0. The process of the loop is executed when the variablei is less than the number of sublayers−1 “MaxNumSubLayers−1”, and everytime the process of the loop is executed, the variable i is incrementedby “1”.

(Step SA123)

The sublayer profile present flag decoding unit 1221 c decodes andoutputs a sublayer profile present flagsub_layer_profile_present_flag[i] regarding the sublayer designated bythe variable i, from the coded data DATA#T.

(Step SA124)

The loop regarding the decoding of the sublayer profile present flag ofthe sublayer is ended.

(Step SA125)

The byte-aligned data decoding unit 1221 e decodes the byte-aligned datafrom the coded data, and moves the decoding start point to the decodingstart point (first bit) of the next syntax.

(Step SA126)

When the profile present flag is 0 (No in step SA121), the sublayerprofile present flag decoding unit 1221 c outputs the sublayer profilepresent flag sub_layer_profile_present_flag[i] of each sublayer i whichis set to 0.

(Step SA127) A loop regarding decoding of a sublayer level present flagof a sublayer is started. Before starting the loop, a variable i isinitialized to 0. The process of the loop is executed when the variablei is less than the number of sublayers−1 “MaxNumSubLayers−1”, and everytime the process of the loop is executed, the variable i is incrementedby “1”.

(Step SA128)

The sublayer level present flag decoding unit 1221 d decodes and outputsa sublayer level present flag sub_layer_level_present_flag[i] regardingthe sublayer designated by the variable i, from the coded data DATA#T.

(Step SA129)

The loop regarding the decoding of the sublayer level present flag isended.

(Step SA130)

The byte-aligned data decoding unit 1221 e decodes the byte-aligned datafrom the coded data, and moves the decoding start point to the decodingstart point (first bit) of the next syntax.

<<Modification 2 of Profile/Level Information Decoding Unit 1211>>

Next, Modification 2 of the profile/level information decoding unit 1211according to Example 1 will be described with reference to FIG. 13 andFIG. 14.

Since a profile/level information decoding unit 1211″ according toModification 2 has the same configuration as in FIG. 1, the descriptionwill be omitted.

FIG. 15 illustrates a data structure of the syntax of profile/levelinformation profile_tier_level( ) which is decoded by the profile/levelinformation decoding unit 1211″, and FIG. 12 is a flowchart illustratinga decoding process of the syntax illustrated in FIG. 15. The differencein the data structures of the profile/level information illustrated inFIG. 15 according to Modification 2 and the profile/level informationillustrated in FIG. 11 according to Example 1 is as follows.

-   -   As illustrated in portions respectively denoted by symbols        SYNA302 and SYNA304 in FIG. 15, syntax related to the level        information, and the tier flag general_tier_flag/sublayer tier        flag sub_layer_tier_flag[i] are signaled so as not to be        dependent on the profile present flag        ProfilePresentFlag/sublayer profile present flag        sub_layer_profile_present_flag[i]. Specifically, the tier flag        general_tier_flag and the level identifier general_level_idc are        signaled, and the sublayer tier flag sub_layer_tier_flag[i] and        the sublayer level identifier sub_layer_level_idc[i] are        signaled. Accordingly, as compared to the related art, without        being dependent on the profile present flag ProfilePresentFlag,        the decoder can acquire constraint of the level determined by        the level identifier general_level_idc and the tier flag        general_tier_flag. Similarly, even in the sublayer, without        being dependent on the profile present flag and the sublayer        profile present flag, the decoder can acquire constraints of the        level determined by the sublayer level identifier        sub_layer_level_idc[i] and the sublayer tier flag        sub_layer_tier_flag[i]. Further, locally the level identifier        and the tier flag are signaled, such that the decoder can easily        specify whether or not the coded data can be decoded.    -   The symbol lengths of the profile space general_profile_space        denoted by the symbol SYNA301 and the sublayer profile space        sub_layer_profile_space[i] denoted by the symbol SYNA303 in FIG.        15 are changed from two bits to three bits, and the symbol        lengths of the level identifier general_level_idc denoted by the        symbol SYNA305 and the sublayer level identifier denoted by the        symbol SYNA306 in FIG. 15 are changed from eight bits to seven        bits such that all of the profile/level information is        byte-aligned. Accordingly, similar to Example 1, since all of        the profile/level information is byte-aligned even in        Modification 2, it is possible to reduce the number of times of        memory access regarding reading/writing when decoding/coding        each syntax of the profile/level information. In other words,        there is an effect of reducing a processing amount required for        decoding/coding the profile/level information. In addition, even        if the symbol lengths of the level identifier/sublayer level        identifier are changed from eight bits to seven bits, since it        is possible to use values from 0 to 127, it is possible to        sufficiently handle the further expansion of the level number.        Further, the symbol length of the profile space is changed to        three bits, such that it is possible to use values from 0 to 7,        and it is possible to have more flexibility for further        expansion of the profile.

Further, similar to Example 1, it is possible to easily extract thesublayer profile information/sublayer level information regarding onlythe specific sublayer X also in Modification 2. In other words, there isan effect of reducing a processing amount required for decoding thesublayer profile information/sublayer level information.

Further, similar to Example 1, also in Modification 2, at a time whenthe profile information regarding a target layer and level informationare decoded, if it is determined that the decoder is capable of decodingthe coded data of a target layer, since the symbol amount of the profileinformation/level information regarding the sublayer can be easilyspecified, it is possible to omit the decoding of the profileinformation/level information regarding the sublayer.

(Flow of Decoding Process of Profile/Level InformationProfile_Tier_Level( ))

Hereinafter, the operation of the profile/level information decodingunit 1211″ according to Modification 2 will be described with referenceto FIG. 12. In addition, with respect to the decoding process of theprofile information/level information, only steps SA102, SA104, SA111,and SA114 in FIG. 12 which are to be changed will be described. Sincethe other steps are common, the description thereof will be omitted. Inother words, in the following description, steps SA102, SA104, SA111,and SA114 in FIG. 12 are respectively replaced with steps SA102′,SA104′, SA111′, and SA114′.

(Step SA102′) The profile information decoding unit 1221 a decodes thesyntax shown in FIG. 15,

-   -   profile space general_profile_space    -   profile identifier general_profile_idc    -   profile capability flag general_profile_compatibility_flag[i],        and    -   profile reserved syntax general_reserved_zero_16bits, from the        coded data DATA#T,

and outputs it as profile information regarding a target layer.

(Step SA104′)

The level information decoding unit 1221 decodes the syntax shown inFIG. 15,

-   -   level identifier general_level_idc,    -   tier flag general_tier_flag,

from the coded data DATA#T,

and outputs it as level information regarding a target layer.

(Step SA111′)

The profile information decoding unit 1221 a decodes and outputs

-   -   sublayer profile space sub_layer_profile_space[i]    -   sublayer profile identifier sub_layer_profile_idc[i]    -   sublayer profile capability flag        sub_layer_profile_compatibility_flag[i][j]    -   sublayer profile reserved syntax        sub_layer_reserved_zero_16bits[i],

as the sublayer profile information regarding the sublayer designated bythe variable i, from the coded data DATA#T.

(Step SA114′)

The level information decoding unit 1221 b decodes and outputs

-   -   sublayer level identifier sub_layer_level_idc[i],    -   sublayer tier flag sub_layer_tier_flag[i],

as the sublayer level information regarding the sublayer which isdesignated by the variable i, from the coded data DATA#T.

<<Modification 2a of Profile/Level Information Decoding Unit 1211>>

In addition, although the symbol lengths of the levelidentifier/sublayer level identifier denoted by symbols SYNA305 andSYNA306 in FIG. 15 are changed from eight bits to seven bits in order tokeep byte-alignment of the profile/level information in Modification 2,it is not limited thereto. The syntax regarding tier, and the tier flaggeneral_tier_flag/sub_layer_tier_flag[i] are expanded from one bit toeight bits, as denoted by the symbols SYN302 a and SYN304 a in FIG. 16,but may be replaced with the tier identifiergeneral_tier_idc/sub_layer_tier_idc[i]. In this case, since the tier hasa value of 0 to 255, it allows the parameters regarding the levelconstraints determined by the level identifier and the tier to havescalability.

<<Modification 3 of Profile/Level Information Decoding Unit 1211>>

In the related art, it is possible to control whether or not to omit thedecoding the profile information, depending on the profile present flag.However, in a case of using a plurality of layers, since layers have acommon level, there is a case of redundantly signaling the levelinformation. Therefore, in order to reduce the redundancy of the signalof the level information, as illustrated in FIG. 17, in the datastructure of the profile/level information profile_tier_level( ), theprofile present flag ProfilePresentFlag is replaced with the profilelevel present flag ProfileLevelPresentFlag indicating whether or not topresent the profile information and the level information, andsimilarly, the sublayer profile present flag and the sublayer levelpresent flag are replaced with the sublayer profile level present flagsub_layer_profile_level_present_flag indicating whether or not topresent the sublayer profile information and the sublayer levelinformation.

Hereinafter, the configuration of the profile/level information decodingunit 1211 in Modification 3 will be described with reference to FIG. 18.As illustrated in FIG. 18, the profile/level information decoding unit1211 includes a profile information decoding unit 1221 a, a levelinformation decoding unit 1221 b, a sublayer profile level present flagdecoding unit 1221 f, and a byte-aligned data decoding unit 1221 e. Inaddition, since the profile information decoding unit 1221 a, the levelinformation decoding unit 1221 b, and the byte-aligned data decodingunit 1221 e are the same as in Example 1, the description thereof willbe omitted. Here, interpretation is performed by respectively replacingthe profile present flag ProfilePresentFlag and the sublayer profilepresent flag/sublayer level present flag in Example 1 with the profilelevel present flag ProfileLevelPresentFlag and the sublayer profilelevel present flag.

[Sublayer Profile Level Present Flag Decoding Unit 1221 f]

The sublayer profile level present flag decoding unit 1221 f decodes thesublayer profile level present flag of each sublayer included in thetarget layer from the coded data DATA#T, based on the profile levelpresent flag ProfileLevelPresentFlag and the number of sublayersMaxNumSubLayers, and outputs it to the profile information decoding unit1221 a, the level information decoding unit 1221 b, and the outside.

(Flow of Decoding Process of Profile/Level InformationProfile_Tier_Level( ))

Hereinafter, the operation of the profile/level information decodingunit 1211 according to Modification 3 will be described with referenceto FIG. 19.

(Step SC101)

The profile information decoding unit 1221 a determines that the profilelevel present flag ProfilelevelPresentFlag is 1. When the profile levelpresent flag ProfileLevelPresentFlag is 1 (Yes in step SC101), theprocess proceeds to step SC102, or in other cases (No in step SC101),the process proceeds to step SC103.

(Step SC102)

The profile information decoding unit 1221 a decodes

-   -   profile space general_profile_space    -   profile identifier general_profile_idc    -   profile capability flag general_profile_compatibility_flag[i]    -   profile reserved syntax general_reserved_zero_16bits, from the        coded data DATA#T, and outputs it as the profile information        regarding a target layer.

The level information decoding unit 1221 b decodes

-   -   level identifier general_level_idc    -   tier flag general_tier_flag, from the coded data DATA#T, and        outputs it as the level information regarding the target layer.

(Step SC103)

The profile information decoding unit 1221 a determines that the profileinformation regarding the target layer is the same as the VPS or theprofile information regarding a lower layer (for example, a base layer),and outputs the VPS or the profile information regarding the lower layerwhich is configured to the profile information regarding the targetlayer.

Further, the level information decoding unit 1221 b determines that thelevel information regarding the target layer is the same as the VPS orthe level information regarding the lower layer (for example, the baselayer), and outputs the VPS or the level information regarding the lowerlayer which is configured to the level information regarding the targetlayer.

(Step SC104)

A loop regarding decoding of a sublayer profile level present flag of asublayer is started. Before starting the loop, a variable i isinitialized to 0. The process of the loop is executed when the variablei is less than the number of sublayers−1 “MaxNumSubLayers−1”, and everytime the process of the loop is executed, the variable i is incrementedby “1”.

(Step SC105)

The sublayer profile present flag decoding unit 1221 f decodes andoutputs a sublayer profile level present flagsub_layer_profile_level_present_flag[i] regarding the sublayerdesignated by the variable i, from the coded data DATA#T.

(Step SC106)

The loop regarding the decoding of the sublayer profile level presentflag is ended.

(Step SC107)

The byte-aligned data decoding unit 1221 e decodes the byte-aligned datafrom the coded data, and moves the decoding start point to the decodingstart point (first bit) of the next syntax.

(Step SC108)

A loop regarding decoding of sublayer profile information and sublayerlevel information regarding a sublayer is started. Before starting theloop, a variable i is initialized to 0. The process of the loop isexecuted when the variable i is less than the number of sublayers−1“MaxNumSubLayers−1”, and every time the process of the loop is executed,the variable i is incremented by “1”.

(Step SC109)

The profile information decoding unit 1221 a determines whether theprofile level present flag ProfileLevelPresentFlag and the sublayerprofile level present flag sub_layer_profile_level_present_flag[i] ofthe sublayer designated by the variable i are both 1. When the profilelevel present flag and the sublayer profile level present flag are both1 (Yes in step SC109), the process proceeds to step SC110, or in othercases, the process proceeds to step SC111.

(Step SC110)

The profile information decoding unit 1221 a decodes

-   -   sublayer profile space sub_layer_profile_space[i]    -   sublayer profile identifier sub_layer_profile_idc[i]    -   sublayer profile capability flag        sub_layer_profile_compatibility_flag[i][j]    -   sublayer profile reserved syntax        sub_layer_reserved_zero_16bits[i], from the coded data DATA#T,        and outputs it as the sublayer profile information regarding the        sublayer designated by the variable i.

Further, the level information decoding unit 1221 b decodes

-   -   sublayer level identifier sub_layer_level_idc[i]    -   sublayer tier flag sub_layer_tier_flag[i], from the coded data        DATA#T, and outputs it as the sublayer level information        regarding the sublayer designated by the variable i.

(Step SC111)

The profile information decoding unit 1221 a determines that thesublayer profile information regarding the sublayer i is the same as theprofile information regarding the target layer, and outputs the sublayerprofile information which is configured to the profile informationregarding the target layer.

Further, the level information decoding unit 1221 b determines that thesublayer level information regarding the sublayer i is the same as thelevel information regarding the target layer, and outputs the sublayerlevel information which is configured to the profile informationregarding the target layer.

(Step SC112)

The loop regarding the decoding of the sublayer profile information andthe sublayer level information regarding the sublayer is ended.

Hitherto, the operation of the profile/level information decoding unit1211 according to Modification 3 has been described, but the operationis not limited to the steps, and the steps may be changed in a feasiblerange.

As described above, similar to Example 1, since all syntax of theprofile/level information is byte-aligned in Modification 3, it ispossible to reduce the number of times of memory access regardingreading/writing when decoding/coding the sublayer profile level presentflag, the sublayer profile information, and the sublayer levelinformation. In other words, there is an effect of reducing a processingamount required for decoding/coding the profile/level information.

Further, since it is possible to reduce the redundancy of the levelinformation, there is an effect of reducing a processing amount requiredfor decoding the profile/level information.

Similar to Example 1, also in Modification 3, at a time when the profileinformation regarding the target layer and the level information aredecoded, if it is determined that the decoder is capable of decoding thecoded data of the target layer, since the symbol amount of the profileinformation/level information regarding the sublayer can be easilyspecified, it is possible to omit the decoding of the profileinformation/level information regarding the sublayer.

Hierarchical Moving Image Coding Device

Hereinafter, the configuration of the hierarchical moving image codingdevice 2 according to the present example will be described withreference to FIGS. 20 to 25.

(Configuration of Hierarchical Moving Image Coding Device)

The description of the schematic configuration of the hierarchicalmoving image coding device 2 by using FIG. 20 is as follows. FIG. 20 isa functional block diagram illustrating a schematic configuration of thehierarchical moving image coding device 2. The hierarchical moving imagecoding device 2 generates the hierarchically coded data DATA of thetarget layer, by coding the input image PIN#T of the target layer whilereferring to the reference layer coded data DATA#R. In addition, it isassumed that the reference layer coded data DATA#R has been coded by thehierarchical moving image coding device corresponding to the referencelayer.

As illustrated in FIG. 20, the hierarchical moving image coding device 2includes a prediction parameter determination unit 21, a predictioninformation generation unit 25, a base decoding unit 23, a textureinformation generation unit 24, a variable length coding unit 22, and anNAL multiplexing unit 26.

[Prediction Parameter Determination Unit 21]

The prediction parameter determination unit 21 determines a predictionparameter used for prediction of a predicted image and anotherconfiguration of coding (header information), based on an input imagePIN#T.

First, the prediction parameter determination unit 21 generates the VPS,the SPS, the PPS, and the slice header, based on the input image PIN#T,and outputs it as header information. In addition, the VPS and the SPSinclude the profile/level information profile_tier_level( ) regardingthe profile and the level required for coding/decoding the target layer.

The prediction parameter determination unit 21 performs theconfiguration of coding based on the prediction parameter as follows.

The prediction parameter determination unit 21 performs the followingprocessing in the profile/level information. The prediction parameterdetermination unit 21 sets the values of the profile present flag of thetarget layer, the profile present flag (sublayer present flag) of thesublayer, and the level present flag (sublayer level present flag) ofthe sublayer, based on the profile information and the level information(profile/level/tier) of the lower layer (for example, base layer), thetarget layer, and each sublayer belonging to the target layer, which aresupplied from the outside or preset, and the supplies the profilepresent flag, and the profile present flag/level present flag of eachsublayer which are set, to the header information coding unit 221.

In addition, if the profile information regarding the lower layer andthe profile information regarding the target layer are the same, or theprofile information regarding the target layer and the profileinformation regarding the sublayer (sublayer profile information) arethe same, it refers to at least the following things.

-   -   The values of the profile spaces are the same    -   The values of the profile identifiers are the same    -   The values of the profile capability flags are the same

Further, if the level information regarding the lower layer and thelevel information regarding the target layer are the same, or the levelinformation regarding the target layer and the level informationregarding the sublayer (sublayer level information) are the same, itrefers to at least the following things.

-   -   The values of the level identifiers are the same    -   The values of the tier flags are the same

In addition, the tier flag may be included in the profile information.In this case, if the profile information pieces are the same, the valuesof the tier flags are the same, in addition to the above constraints.

The ProfilePresentFlag indicating whether or not to explicitly codingthe profile information is determined as follows. When the profileinformation regarding the lower layer and the profile informationregarding the target layer are the same, the profile informationregarding the target layer is configured from the profile of apredetermined layer, such that the profile present flag is set to 0, andotherwise, the profile present flag is set to 1 in order to explicitlycode the profile information regarding the target layer.

Subsequently, when the profile present flag is 1, the profile presentflag (sublayer profile present flag) of each sublayer is determined asfollows. When the profile information regarding the target layer and thesublayer profile information regarding the sublayer are the same, inorder to configure the sublayer profile information regarding thesublayer from the profile information regarding the target layer, thesublayer profile present flag is set to 0, and otherwise, the sublayerprofile present flag is set to 1 in order to explicitly code thesublayer profile information regarding the sublayer.

Further, the level present flag (sublayer level present flag) of eachsublayer is determined as follows. When the level information regardingthe target layer and the sublayer level information regarding thesublayer are the same, in order to configure the sublayer levelinformation regarding the sublayer from the level information regardingthe target layer, the sublayer level present flag is set to 0, andotherwise, the sublayer level present flag is set to 1 in order toexplicitly code the sublayer profile information regarding the sublayer.

In addition, the prediction parameter determination unit 21 maydetermine the profile information, the profile level present flagindicating whether or not to present the level information, the sublayerprofile information, and the sublayer profile level present flagindicating whether or not to present the sublayer level information,instead of the profile present flag, the sublayer profile present flag,and the sublayer level present flag, and supplies the determinedinformation to the header information coding unit 221.

In other words, the ProfileLevelPresentFlag indicating whether or not toexplicitly code the profile information and the level information isdetermined as follows. If the profile information and the levelinformation regarding the lower layer and the profile information andthe level information regarding the target layer are respectively thesame, since the profile information and the level information regardingthe target layer are configured from the profile information and thelevel information regarding a predetermined layer, the profile levelpresent flag is set to 0, or otherwise, the profile level present flagis set to 1 in order to explicitly code the profile information and thelevel information regarding the target layer.

Subsequently, when the profile level present flag is 1, the profilelevel present flag of each sublayer (sublayer profile level presentflag) is determined as follows. When the profile information and thelevel information regarding the target layer and the sublayer profileinformation and the sublayer level information regarding the sublayerare respectively the same, in order to configure the sublayer profileinformation and the sublayer level information regarding the sublayerfrom the profile information and the level information regarding thetarget layer, the sublayer profile present flag is set to 0, orotherwise, the sublayer profile present flag is set to 1 in order toexplicitly code the sublayer profile information regarding the sublayer.

First, the prediction parameter determination unit 21 generates the CUimage for the target CU, by sequentially splitting the input image PIN#Tinto the slice unit, the tree block unit, and the CU unit.

Further, the prediction parameter determination unit 21 generates thecoding information (referred to as header information), based on theresult of the split process. The coding information includes (1) treeblock information which is information regarding the size and shape ofthe tree block belonging to the target slice and the position of thetree block in the target slice, and (2) CU information which isinformation regarding the size and shape of the CU belonging to eachtree block and the position of the CU in the target tree block.

Further, the prediction parameter determination unit 21 derives theprediction type of the target CU, the split information regarding thetarget CU to the PU, and the prediction parameter, by referring to theCU image, the tree block information, and the CU information (when thetarget CU is the intra-CU, the intra-prediction mode; when the target CUis the inter-CU, the motion compensation parameter of each PU).

The prediction parameter determination unit 21 calculates the cost for acombination of all of (1) the prediction type of the target CU, (2) theavailable splitting pattern of the target CU to each PU, and (3) theprediction mode which can be assigned to each PU (in the case of theintra-CU, the intra-prediction mode; in the case of the inter-CU, themotion compensation parameter), and determines the prediction type, thesplit pattern, and the prediction mode of the lowest cost.

The prediction parameter determination unit 21 supplies the codinginformation and the prediction parameter to the prediction informationgeneration unit 25 and the texture information generation unit 24. Inaddition, although not shown for convenience of explanation, theconfiguration of the coding which is determined in the predictionparameter determination unit 21 can be referred in each unit of thehierarchical moving image coding device 2.

[Prediction Information Generation Unit 25]

The prediction information generation unit 25 generates predictioninformation including a syntax value regarding the prediction parameter,based on the prediction parameter supplied from the prediction parameterdetermination unit 21 and the reference layer coded data DATA#R. Theprediction information generation unit 25 supplies the generatedprediction information to the variable length coding unit 22. Inaddition, when the prediction parameter is restored, the predictioninformation generation unit 25 can refer to the inter-predictionparameter stored in the frame memory (described later) included in thetexture information generation unit 24. In addition, the details of theprediction information generation unit 25 will be described later.

[Base Decoding Unit 23]

Since the base decoding unit 23 is the same as the base decoding unit 16of the hierarchical moving image decoding device 1, here, thedescription thereof will be omitted.

[Texture Information Generation Unit 24]

The texture information generation unit 24 generates the transformcoefficient information including the transform coefficient byperforming orthogonal transform and quantization on the predictionresidual obtained by subtracting the predicted image from the inputimage PIN#T. The texture information generation unit 24 supplies thegenerated transform coefficient information to the variable lengthcoding unit 22. In addition, information regarding the decoded imagewhich is restored is stored in the frame memory included in the insideof the texture information generation unit 24.

[Variable Length Coding Unit 22]

The variable length coding unit 22 generates target layer coded dataDATA#T by variable length coding the header information supplied fromthe prediction parameter determination unit 21, the predictioninformation supplied from the prediction information generation unit 25and the transform coefficient information supplied from the textureinformation generation unit 24. The variable length coding unit 22supplies the generated target layer coded data DATA#T to the NALmultiplexing unit 26.

Specifically, as illustrated in FIG. 21, the variable-length coding unit22 includes a header information coding unit 221, a predictioninformation coding unit 222, and a transform coefficient informationcoding unit 223. Further, the header information coding unit 221includes a profile/level information coding unit 2211.

[Header Information Coding Unit 221]

The header information decoding unit 221 outputs coded data of headerinformation by coding the header information regarding parameters usedfor coding per sequence, per picture, or per slice, in the reverseprocess of the header information coding unit 121. In addition, thedetails of the profile/level information coding unit 2211 included inthe header information coding unit 221 will be described later.

[Prediction Information Coding Unit 222]

The prediction information coding unit 222 outputs coded data of theprediction information by coding the prediction information regardingeach CU or PU, in the reverse process of the prediction informationdecoding unit 122.

The prediction information includes, for example, information fordesignating a CU type or a PU type, and information for specifying theshape, the size, and the position of the CU.

[Transform Coefficient Information Coding Unit 223]

The transform coefficient information coding unit 223 outputs the codeddata of transform coefficient information by coding the transformcoefficient information such as a quantization prediction residual QDfor each block and a quantization parameter difference Δqp for a treeblock including the block, in the reverse process of the transformcoefficient information decoding unit 123.

[NAL Multiplexing Unit 26]

The NAL multiplexing unit 26 generates a hierarchical moving image codeddata DATA which is NAL-multiplexed by storing the target layer codeddata DATA#T supplied from the variable-length coding unit 22 and thereference layer coded data DATA#R in the NAL unit, and outputs thegenerated image to the outside. In addition, coded data which isVCL-coded, and a header for properly delivering the coded data to thelower system which is the destination (NAL unit header: nal_unit_header()) are added to the NAL unit.

Hereinafter, the respective details of the prediction informationgeneration unit 25 and the texture information generation unit 24 willbe described.

(Prediction Information Generation Unit)

The detailed configuration of the prediction information generation unit25 will be described with reference to FIG. 22. FIG. 22 is a functionalblock diagram illustrating a configuration of the prediction informationgeneration unit 25.

As illustrated in FIG. 22, the prediction information generation unit 25includes a prediction type selection unit 251, a switch 252, anintra-prediction information generation unit 253, and aninter-prediction information generation unit 255.

The prediction type selection unit 251 sends a switching instruction inresponse to a CU type or a PU type to the switch 252 so as to controlthe derivation process of the prediction parameter. The details are asfollows.

When the intra-CU or the intra-PU is not designated, the prediction typeselection unit 251 controls the switch 252 so as for theintra-prediction information generation unit 253 to generateintra-prediction information (prediction information).

When any of the inter-CU and the inter-PU is not designated, theprediction type selection unit 251 controls the switch 252 so as for theinter-prediction information generation unit 255 to generateinter-prediction information.

The switch 252 supplies the prediction parameter to any of theintra-prediction information generation unit 253 and theinter-prediction information generation unit 255, in response to theinstruction of the prediction type selection unit 251. The predictioninformation is generated in the supply destination of the predictionparameter.

The intra-prediction information generation unit 253 derives a syntaxvalue regarding the intra-prediction mode. In other words, theintra-prediction information generation unit 253 generates the syntaxvalue regarding the prediction mode as the prediction information.

The inter-prediction information generation unit 255 derives motionvector candidates which are estimated by an intra-layer motionestimation process or an inter-layer motion estimation process, by usingthe base decoding information. Subsequently, inter_pred_flag, mvd, anmvp_idx, and refIdx which are corresponding syntax element values arederived from the inter-prediction parameter of each PU, and are outputas the inter-prediction information.

(Texture Information Generation Unit)

The detailed configuration of the texture information generation unit 24will be described with reference to FIG. 23. FIG. 23 is a functionalblock diagram illustrating a configuration of the texture informationgeneration unit 24.

As illustrated in FIG. 23, the texture information generation unit 24includes a texture prediction unit 241, a subtractor 242, an orthogonaltransform and quantization unit 243, an inverse orthogonal transform andinverse quantization unit 244, an adder 245, a loop filter unit 246, anda frame memory 247.

The subtractor 242 generates a prediction residual D by subtracting thepredicted image supplied from the texture prediction unit 241, from theinput image PIN#T. The subtractor 242 supplies the generated predictionresidual D to the orthogonal transform and quantization unit 243.

The orthogonal transform and quantization unit 243 generates thequantized prediction residual by performing the orthogonal transform andquantization on the prediction residual D. In addition, here, theorthogonal transform means the orthogonal transform from the pixelregion to the frequency region. Further, examples of the orthogonaltransform include discrete cosine transform (DCT transform), discretesine transform (DST transform), and the like. Further, a specificquantization process is as described already, and thus the descriptionthereof will be omitted here. The orthogonal transform and quantizationunit 243 supplies the transform coefficient information including thequantized prediction residual which is generated to the inverseorthogonal transform and inverse quantization unit 244 and the variablelength coding unit 22.

Since the texture prediction unit 241, the inverse orthogonal transformand inverse quantization unit 244, the adder 245, the loop filter unit246, and the frame memory 247 are respectively the same as the textureprediction unit 152, the inverse orthogonal transform and inversequantization unit 151, the adder 153, the loop filter unit 154, and theframe memory 155 which are included in the hierarchical moving imagedecoding device 1, the description thereof will be omitted here. Here,the texture prediction unit 241 supplies the predicted image not only tothe adder 245 but also to the subtractor 242.

Example 1 Details of Profile/Level Information Coding Unit 2211

Next, the configuration of the profile/level information coding unit2211 according to Example 1 which is the reverse process of theprofile/level information decoding unit 1211 according to Example 1 willbe described with reference to FIG. 24.

FIG. 24 is a functional block diagram illustrating a configuration ofthe profile/level information coding unit 2211. As illustrated in FIG.24, the profile/level information coding unit 2211 includes a profileinformation coding unit 2221 a, a level information coding unit 2221 b,a sublayer profile present flag coding unit 2221 c, a sublayer levelpresent flag coding unit 2221 d, and a byte-aligned data coding unit2221 e. In addition, the profile/level information coding unit 2211according to Example 1 codes the profile information, the levelinformation, the sublayer profile present flag, the sublayer levelpresent flag, the sublayer profile information, the sublayer levelinformation, and the byte-aligned data, in respective functional blocks,according to the syntax definition of the profile/level informationprofile_tier_level( ) illustrated in FIG. 11.

[Profile Information Coding Unit 2221 a]

The profile information coding unit 2221 a codes profile informationregarding the target layer which is supplied from the outside based onthe profile present flag ProfilePresentFlag, and outputs the coded data.Specifically, when the profile present flag ProfilePresentFlag is 1, theprofile information regarding the target layer is coded. When theprofile present flag ProfilePresentFlag is 0, the profile information isnot coded.

Further, the profile information coding unit 2221 a codes the sublayerprofile information regarding each sublayer which is supplied from theoutside, based on the profile present flag ProfilePresentFlag, thenumber of sublayers MaxNumSubLayers, and the sublayer profile presentflag of each sublayer sub_layer_profile_preset_flag[i]. Specifically,when the profile present flag is 1, and the sublayer profile presentflag of the sublayer i (temporalId=i+1) is 1, the corresponding sublayerprofile information is coded. Otherwise, the sublayer profileinformation regarding the sublayer i is not coded.

[Level Information Coding Unit 2221 b]

The level information coding unit 2221 b codes the level informationregarding the target layer which is supplied from the outside, andoutputs the coded data. Further, the level information coding unit 2221b codes the sublayer level information regarding each sublayer which issupplied from the outside, based on the number of sublayersMaxNumSubLayers, and the sublayer level present flag of each sublayersub_layer_level_present_flag[i], and outputs the coded data.Specifically, when the sublayer level present flagsub_layer_level_present_flag[i] is 1, the sublayer level informationregarding the corresponding sublayer i (temporalId=i+1) is coded.Otherwise (sublayer level present flag sub_layer_level_present_flag[i]is 0), the sublayer level information regarding the sublayer i is notcoded.

[Sublayer Profile Present Flag Coding Unit 2221 c]

The sublayer profile present flag coding unit 2221 c codes the sublayerprofile present flag of each sublayer which is supplied from theoutside, based on the number of sublayers MaxNumSubLayers, and outputsthe coded flag.

[Sublayer Level Present Flag Coding Unit 2221 d]

The sublayer level present flag coding unit 2221 d codes the sublayerlevel present flag of each sublayer which is supplied from the outside,based on the number of sublayers MaxNumSubLayers, and outputs the codedflag.

[Byte-Aligned Data Coding Unit 2221 e]

Until the current position (per bit) of the coded data is a byteboundary, in other words, a bit located in the next position of thecurrent position on the coded data is a first bit of a byte, thebyte-aligned data coding unit 2221 e inserts (codes) the byte-aligneddata alignment_bit per bit into the coded data.

<<Modification 1>>

Hereinafter, a configuration of the profile/level information codingunit 2211 corresponding to Modification 1 of the profile/levelinformation decoding unit 1211 according to Example 1 will be described.

Further, the profile/level information coding unit 2211 may code theprofile/level information as follows, in addition to the profile/levelinformation profile_tier_level( ) shown in FIG. 11, for example, asillustrated in FIG. 13,

-   -   As illustrated in the portions respectively denoted by the        symbols SYNA201 and SYNA202 in FIG. 13, the sublayer profile        present flag and the sublayer level present flag are separately        signaled,    -   As illustrated in the portion denoted by the symbol SYNA201 in        FIG. 13, only when the profile present flag is 1, the sublayer        profile present flag is signaled,    -   As illustrated in the portions respectively denoted by the        symbols SYNA201 and SYNA202 in FIG. 13, byte-aligned data is        inserted respectively after the sublayer profile present flag        and the sublayer level present flag. In this case, when the        profile present flag ProfilePresentFlag is 0, since the sublayer        profile present flag of the sublayer is not coded, as compared        to the related art, there is an effect of reducing the symbol        amount regarding the profile/level information.

Further, since all of the profile/level information is byte-aligned, itis possible to reduce the number of times of memory access regardingreading/writing when decoding/coding the sublayer profile present flag,the sublayer level present flag, the sublayer profile information, andthe sublayer level information. In other words, there is an effect ofreducing a processing amount required for decoding/coding theprofile/level information.

<<Modification 2>>

Hereinafter, a configuration of the profile/level information codingunit 2211 corresponding to Modification 2 of the profile/levelinformation decoding unit 1211 according to Example 1 will be described.

Further, the profile/level information coding unit 2211 may code theprofile/level information as follows, in addition to the profile/levelinformation profile_tier_level( ) shown in FIG. 11, for example, asillustrated in FIG. 15,

-   -   As illustrated in the portions respectively denoted by the        symbols SYNA302 and SYNA304 in FIG. 15, the tier flag        general_tier_flag, the level identifier general_level_idc, the        sublayer tier flag sub_layer_tier_flag[i], and the sublayer        level identifier sub_layer_level_idc[i] are respectively        signaled such that the signals of the syntax, and the tier flag        general_tier_flag/sublayer tier flag sub_layer_tier_flag[i]        which are related to the level information are not be dependent        on the profile present flag ProfilePresentFlag/sublayer profile        present flag sub_layer_profile_present_flag[i],    -   Profile/level information in which the symbol lengths of the        profile space general_profile_space denoted by the symbol        SYNA301 and the sublayer profile space        sub_layer_profile_space[i] denoted by the symbol SYNA303 in FIG.        15 are changed from two bits to three bits, and the symbol        lengths of the level identifier general_level_idc denoted by the        symbol SYNA305 and the sublayer level identifier denoted by the        symbol SYNA306 in FIG. 15 are changed from eight bits to seven        bits may be coded such that all of the profile/level information        is byte-aligned.

In this case, the decoder can acquire a constraint of a level determinedby the level identifier general_level_idc and the tier flaggeneral_tier_flag, without being dependent on the value of the profilepresent flag ProfilePresentFlag.

Similarly, also in the sublayer, the decoder can acquire a constraint ofa level determined by the sublayer level identifiersub_layer_level_idc[i] and the sublayer tier flagsub_layer_tier_flag[i], without being dependent on the values of theprofile present flag and the sublayer profile present flag. In otherwords, locally the level identifier and the tier flag are signaled, suchthat the decoder can easily specify whether or not the coded data can bedecoded. Further, since all of the profile/level information isbyte-aligned, it is possible to reduce the number of times of memoryaccess regarding reading/writing when decoding/coding each syntax of theprofile/level information. In other words, there is an effect ofreducing a processing amount required for decoding/coding theprofile/level information.

<<Modification 2a>>

Hereinafter, a configuration of the profile/level information codingunit 2211 corresponding to Modification 2 a of the profile/levelinformation decoding unit 1211 according to Example 1 will be described.

Further, the profile/level information coding unit 2211 may code theprofile/level information in which the syntax, and the tier flaggeneral_tier_flag/sub_layer_tier_flag[i] regarding the tier tier,instead of the profile/level information illustrated in FIG. 15, arerespectively replaced with the tier identifiersgeneral_tier_idc/sub_layer_idc[i] which are expanded from one bit toeight bits as denoted by symbols SYN302 a and SYN304 a in FIG. 16. Inthis case, since the tier has the values of 0 to 255, it allows theparameters regarding the level constraints determined by the levelidentifier and the tier to have scalability. Further, since all of theprofile/level information is byte-aligned, it is possible to reduce thenumber of times of memory access regarding reading/writing whendecoding/coding each syntax of the profile/level information. In otherwords, there is an effect of reducing a processing amount required fordecoding/coding the profile/level information.

<<Modification 3>>

Hereinafter, a configuration of the profile/level information codingunit 2211 corresponding to Modification 3 of the profile/levelinformation decoding unit 1211 according to Example 1 will be described.

Further, in order to reduce the redundancy of the signal of the levelinformation, as illustrated in FIG. 17, the profile/level informationcoding unit 2211 may code the syntax of the profile/level informationprofile_tier_level( ) in which the profile present flagProfilePresentFlag is replaced with the profile level present flagProfileLevelPresentFlag indicating whether or not to present the profileinformation and the level information, and similarly, the sublayerprofile present flag and the sublayer level present flag are replacedwith the sublayer profile level present flagsub_layer_profile_level_present_flag indicating whether or not topresent the sublayer profile information and the sublayer levelinformation. In this case, as illustrated in FIG. 25, the profile/levelinformation coding unit 2211 includes a profile information coding unit2221 a, a level information coding unit 2221 b, a sublayer profile levelpresent flag coding unit 2221 f, and a byte-aligned data coding unit2221 e. In addition, since the profile information coding unit 2221 a,the level information coding unit 2221 b, and the byte-aligned datacoding unit 2221 e are the same as in Example 1, the description thereofwill be omitted. However, it is assumed that the profile present flagProfilePresentFlag in Example 1 is interpreted by being replaced withthe profile level present flag ProfileLevelPresentFlag, and the sublayerprofile present flag/sublayer level present flag is interpreted by beingreplaced with the sublayer profile level present flag. [Sublayer profilelevel present flag decoding unit 2221 f]

The sublayer profile level present flag coding unit 2221 f codes thesublayer profile level present flag of each sublayer, based on theprofile level present flag ProfileLevelPresentFlag and the number ofsublayers MaxNumSubLayers, and outputs the coded data.

(Notes)

Further, in the related art (NPL 1), since there is no constraintbetween the sublayer profile information and the sublayer levelinformation regarding the sublayer (sublayer profile/sublayerlevel/sublayer tier) and the profile information and the levelinformation (profile/level/tier) to be referred to in order to decodethe target layer, there is a problem in that the implementation load ofthe image decoding device is high (the complexity of the image decodingdevice is increased). For example, it is assumed that in FIG. 3(a), theprofile of the target layer L#N and respective sublayer profiles of thesublayers SL#4 to SL#1 included in the target layer L#N are coded byconfiguration of three types of profiles as follows,

the profile of the target layer L#N: “high profile”,

the profile (sublayer profile) of the sublayer SL#1: “base profile”,

the profile (sublayer profile) of the sublayer SL#2: “high profile”,

the profile (sublayer profile) of the sublayer SL#3: “high profile”, and

the profile (sublayer profile) of the sublayer SL#4: “main profile”.Here, it is assumed that “high profile” is a higher profile ofsupporting all coding tools of “main profile”, and “main profile” is ahigher profile of supporting all coding tools of “base profile”. Inother words, the relationship between the profiles is “baseprofile”<“main profile”<“high profile”.

In the case of this example, in the image decoding device supporting theprofile “high profile”, it is possible to decode the sublayers SL#1 toSL#4 in the target layer L#N. In other words, it is possible tocompletely decode the target layer L#N. However, in the image decodingdevice supporting the profile “main profile”, since the profiles of thelower sublayers (SL#2, SL#3) are not compatible with the profile of thehigher sublayer (SL#4), it is not possible to decode the lower sublayers(SL#2, SL#3) on which the sublayer SL#4 is dependent during decoding ofthe sublayer SL#4, and the higher sublayer SL#4, and it is possible todecode only the lowest sublayer SL#1 which is the lower profile “baseprofile”. In other words, there is a possibility in that the imagecoding device generates coded data in which profiles are discontinuouslyconfigured in which the profile of the lower sublayer is not compatiblewith the profile of the higher sublayer. Therefore, when the imagedecoding device decodes the coded data, it is not possible to decode thelower sublayer to be decoded on which another sublayer is dependent, andas a result, there is a problem in that the granularity of timescalability becomes rough.

Further, in order for the image decoding device to flexibly realizescalability for such coded data, it needs to be implemented to support aplurality of profiles, such that there is a problem in that thecomplexity of the image decoding device is increased.

Thus, in order to solve the problem, it is preferable to provide thefollowing constraints for the profile of the target layer and theprofiles of the sublayers belonging to the target layer (sublayerprofiles).

(1-1) Configuring the profile of the target layer so as to be the sameas the profile of the highest sublayer included in the target layer.

(1-2) Configuring the profile of the higher sublayer to be equal to orgreater than the profile of the lower sublayer on which the highersublayer is dependent during decoding.

The image decoding device and the image coding device configure inadvance the constraints of the profiles, such that there is an effect ofpreventing the generation of the coded data in which profiles arediscontinuously configured in which the profile of the lower sublayer isnot compatible with the profile of the higher sublayer. Further, sinceit is possible to suppress the profile to which the image decodingdevice corresponds, to a necessary minimum value, there is an effect ofreducing the complexity of the image decoding device.

Further, the syntax (profile constraint flag “profile_restrict_flag”)indicating whether or not to perform the constraint regarding theprofile of the target layer and the profile of the sublayer belonging tothe target layer may explicitly be decoded/coded by the headerinformation decoding unit 121 and the header information coding unit221, immediately before the profile/level informationprofile_tier_level( ), in the sequence layer such as the video parameterset VPS or the sequence parameter set SPS. In addition to the sameeffect described above, there is an effect that the image decodingdevice can easily determine whether there is the profile constraint ateach layer on the VPS or the SPS in advance, prior to decoding theprofile/level information profile_tier_level( ).

Similarly, with respect to the level/tier, since there is no constraintbetween the level/tier of the target layer and the sublayerlevel/sublayer tier of the sublayer belonging to the target layer, thesame problem as in the case without the profile constraint occurs. Inother words, there is a possibility in that the image coding devicegenerates coded data in which the level and the tier are discontinuouslyset in which the level and the tier of the lower sublayer is notcompatible with the level and the tier of the higher sublayer, and thereis a problem in that the granularity of time scalability becomes roughand flexibility is impaired in the image decoding device.

Further, in order for the image decoding device to flexibly realize thescalability for the coded data, it needs to be implemented to support aplurality of levels and tiers, and thus there is a problem of anincrease in the complexity of the image decoding device.

Thus, in order to solve the problem, it is preferable to provide thefollowing constraints between the level/tier of the target layer and thelevels/tiers of the sublayers belonging to the target layer (sublayerlevel/sublayer tier).

The constraints regarding a level is

(2-1) Setting the level of the target layer so as to be the same as thelevel of the highest sublayer included in the target layer.

(2-2) Setting the level of the higher sublayer to be equal to or greaterthan the level of the lower sublayers on which the higher sublayer isdependent during decoding.

The constraints regarding a tier is

(3-1) Setting the tier of the target layer so as to be the same as thetier of the highest sublayer included in the target layer.

(3-2) Setting the tier of the higher sublayer to be equal to or greaterthan the tier of the lower sublayers on which the higher sublayer isdependent during decoding.

The image decoding device and the image coding device configure inadvance the constraints of the level/tier, such that there is an effectof preventing the generation of the coded data in which levels arediscontinuously set in which the level and the tier of the lowersublayer are not compatible with the level and the tier of the highersublayer. Further, since it is possible to suppress the level and thetier to which the image decoding device corresponds, to necessaryminimum values, there is an effect of reducing the complexity of theimage decoding device.

Further, the syntax (level tier constraint flag“level_tier_restrict_flag”) indicating whether or not to perform theconstraint regarding the tier/level of the target layer and thetier/level of the sublayer belonging to the target layer may explicitlybe decoded/coded by the header information decoding unit 121 and theheader information coding unit 221, immediately before the profile/levelinformation profile_tier_level( ), in the sequence layer such as thevideo parameter set VPS or the sequence parameter set SPS. In additionto the same effect described above, there is an effect of being able toeasily determine whether there is the level/tier constraint at eachlayer on the VPS or the SPS in advance.

Further, the image decoding device and the image coding device set inadvance the profile constraint and the level/tier constraints, such thatthere is an effect of preventing the generation of coded data in whichlevels are discontinuously set in which the profile, the level, and thetier of the lower sublayer are not compatible with the profile, thelevel and the tier of the higher sublayer. Further, since it is possibleto suppress the profile, the level, and the tier to which the imagedecoding device corresponds, to necessary minimum values, there is aneffect of reducing the complexity of the image decoding device.

Further, syntax (profile level tier constraint flag“profile_level_tier_restrict_flag”) indicating whether or not to performthe profile constraint and the level/tier constraints may respectivelyexplicitly be decoded/coded by the header information decoding unit 121and the header information coding unit 221, immediately before theprofile/level information (profile_tier_level( ), in the sequence layersuch as the video parameter set VPS or the sequence parameter set SPS.In addition to the same effect described above, there is an effect thatthe image decoding device can easily determine whether there is theprofile constraint and the level/tier constraints at each layer on theVPS or the SPS in advance, prior to decoding the profile/levelinformation profile_tier_level( ).

(Application Example to Another Hierarchical Moving ImageCoding/Decoding System)

The hierarchical moving image coding device 2 and the hierarchicalmoving image decoding device 1 which are described above can be used bybeing mounted in various devices that perform transmission, reception,recording, and playing of the moving image. In addition, the movingimage may be a natural moving image which is captured by a camera andthe like, or an artificial moving image (including a CG and a GUI) whichis generated by a computer or the like.

First, a fact that the hierarchical moving image coding device 2 and thehierarchical moving image decoding device 1, which are described above,can be used for transmitting and receiving a moving image will bedescribed with reference to FIG. 26.

(a) of FIG. 26 is a block diagram illustrating a configuration of atransmission device PROD-A equipped with the hierarchical moving imagecoding device 2. As illustrated in (a) of FIG. 26, the transmissiondevice PROD-A includes a coding unit PROD-A1 that obtains coded data bycoding a moving image, a modulation unit PROD-A2 that obtains amodulation signal by modulating a carrier with the coded data obtainedby the coding unit PROD-A1, and a transmission unit PROD-A3 thattransmits the modulation signal obtained by the modulation unit PROD-A2.The hierarchical moving image coding device 2 described above is used asthe coding unit PROD-A1.

The transmission device PROD-A may further include a camera PROD-A4 thatcaptures a moving image, as a source of a moving image to be input tothe coding unit PROD-A1, a recording medium PROD-A5 that records amoving image, an input terminal PROD-A6 for inputting a moving imagefrom an outside, and an image processing unit A7 that generates andprocesses an image. (a) of FIG. 26 illustrates a configuration in whichthe transmission device PROD-A includes all these, but some parts may beomitted.

In addition, the recording medium PROD-A5 may record the moving imagewhich is not coded, or may record a moving image which has been coded bya coding scheme for recording different from the coding scheme fortransmission. In the latter case, a decoding unit (not shown) thatdecodes the coded data which is read from the recording medium PROD-A5according to the coding scheme for recording may be interposed betweenthe recording medium PROD-A5 and the coding unit PROD-A1.

(b) of FIG. 26 is a block diagram illustrating a configuration of areception device PROD-B equipped with the hierarchical moving imagedecoding device 1. As illustrated in (b) of FIG. 26, the receptiondevice PROD-B includes a reception unit PROD-B1 that receives amodulation signal, a demodulation unit PROD-B2 that obtains coded databy demodulating the modulation signal received by the reception unitPROD-B1, and a decoding unit PROD-B3 that obtains a moving image bydecoding the coded data obtained by the demodulation unit PROD-B2. Thehierarchical moving image decoding device 1 described above is used asthe decoding unit PROD-B3.

The reception device PROD-B may further include a display PROD-B4 thatdisplays a moving image, as a source of the moving image that is outputby the decoding unit PROD-B3, a recording medium PROD-B5 that recordsthe moving image, and an output terminal PROD-B6 for outputting themoving image to the outside. (b) of FIG. 26 illustrates a configurationin which the reception device PROD-B includes all these, but some partsmay be omitted.

In addition, the recording medium PROD-B5 may record the moving imagewhich is not coded, or may be a moving image which has been coded by acoding scheme for recording different from the coding scheme fortransmission. In the latter case, a coding unit (not shown) that codesthe moving image which is acquired from the decoding unit PROD-B3according to the coding scheme for recording may be interposed betweenthe decoding unit PROD-B3 and the recording medium PROD-B5.

In addition, the transmission medium for transmitting the modulationsignal may be a wireless transmission medium, and a wired transmissionmedium. Further, the transmission mode for transmitting the modulationsignal may be broadcasting (here, indicating a transmission mode inwhich a transmission destination is not specified in advance) andcommunication (here, indicating a transmission mode in which atransmission destination is not specified in advance). In other words,the transmission of the modulation signal may be realized by any ofwireless broadcasting, wired broadcasting, wireless communication, andwireless communication.

For example, a broadcasting station (such as broadcasting equipment)/areceiving station (such as a television receiver) of terrestrial digitalbroadcasting are an example of the transmission device PROD-A/receptiondevice PROD-B that respectively transmits and receives a modulationsignal in radio broadcasting. Further, a broadcasting station (such asbroadcasting equipment)/a receiving station (such as a televisionreceiver) of cable television broadcasting are an example of thetransmission device PROD-A/reception device PROD-B that respectivelytransmits and receives a modulation signal in wired broadcasting.

A server (such as a workstation)/a client (a television receiver, apersonal computer, a smart phone, and the like) of a video on demand(VOD) service and a moving image sharing service using an inter-networkare an example of the transmission device PROD-A/reception device PROD-Bthat respectively transmits and receives a modulation signal incommunication (typically, either wired or wireless is used as atransmission medium in a LAN, and a wired can be used as a transmissionmedium in a WAN). Here, examples of the personal computer include adesktop PC, a laptop PC, and a tablet PC. Further, examples of the smartphone include a multi-functional mobile phone terminal.

In addition, the client of the moving image sharing service has afunction of coding a moving image which has been captured by a cameraand uploading the image to the server, in addition to a function ofdecoding coded data which has been downloaded from the server anddisplays the data on a display. In other words, the client of the movingimage sharing service functions as both the transmission device PROD-Aand the reception device PROD-B.

Next, the recording and playback of a moving image by the hierarchicalmoving image coding device 2 and the hierarchical moving image decodingdevice 1 that are described above will be will be described withreference to FIG. 27.

(a) of FIG. 27 is a block diagram illustrating a configuration of therecording device PROD-C equipped with the hierarchical moving imagecoding device 2 described above. As illustrated in (a) of FIG. 27, therecording device PROD-C includes the coding unit PROD-C1 that obtainscoded data by coding a moving image, and the writing unit PROD-C2 thatwrites the coded data obtained by the coding unit PROD-C1 to therecording medium PROD-M. The hierarchical moving image coding device 2described above is used as the coding unit PROD-C1.

In addition, the recording medium PROD-M, (1) may be a type incorporatedin the recording device PROD-C, such as the hard disk drive (HDD) and asolid state drive (SDD), (2) may also be a type that is connected to therecording device PROD-C, such as an SD memory card, and a universalserial bus (USB) flash memory, or (3) may be mounted on a drive device(not shown) incorporated in the recording device PROD-C, such as adigital versatile disc (DVD) or a Blu-ray Disc (BD (registeredtrademark)).

Further, the recording device PROD-C may further include a cameraPROD-C3 capturing a moving image, an input terminal PROD-C4 inputting anmoving image from the outside, the reception unit PROD-C5 receiving anmoving image, and the image processing unit C6 generating or processingan image, as a source of a moving images to be input to the coding unitPROD-C1. In (a) of FIG. 27, all these are exemplified as componentsincluded in the recording device PROD-C, but some may be omitted.

In addition, the reception unit PROD-C5 may receive a moving image thathas not be coded, and may receive coded data which has been coded in atransmission coding scheme different from a recording coding scheme. Inthe latter case, a transmission decoding unit (not shown) that decodesthe coded data in the transmission coding scheme may be interposedbetween the reception unit PROD-C5 and the coding unit PROD-C1.

Examples of the recording device PROD-C include, for example, a DVDrecorder, a BD recorder, and a hard disk drive (HDD) recorder (in thiscase, the input terminal PROD-C4 or the reception unit PROD-C5 are themain source of a moving image). Further, a camcorder (in this case, thecamera PROD-C3 is the main source of a moving image), a personalcomputer (in this case, the reception unit PROD-C5 or the imageprocessing unit C6 are the main source of a moving image), a smart phone(in this case, the camera PROD-C3 or the reception unit PROD-C5 are themain source of the moving image) and the like are the examples of therecording device PROD-C.

(b) of FIG. 27 is a block diagram illustrating a configuration of aplayback device PROD-D equipped with the hierarchical moving imagedecoding device 1 described above. As illustrated in (b) of FIG. 27, theplayback device PROD-D includes a reading unit PROD-D1 that reads codeddata that is written in the recording medium PROD-M, and a decoding unitPROD-D2 that obtains a moving image by decoding the coded data that isread by the reading unit PROD-D1. The hierarchical moving image decodingdevice 1 described above is used as the decoding unit PROD-D2.

In addition, the recording medium PROD-M (1) may be a type incorporatedin the playback device PROD-D such as a HDD or an SSD, (2) may also be atype that is connected to the playback device PROD-D, such as an SDmemory card, or a USB flash memory, or (3) may be mounted on a drivedevice (not shown) incorporated in the playback device PROD-D, such as aDVD or a BD.

Further, the playback device PROD-D may further include a displayPROD-D3 displaying a moving image, an output terminal PROD-D4 outputtinga moving image to the outside, and a transmission unit PROD-D5transmitting a moving image, as a source of a moving image that isoutput by the decoding unit PROD-D2. In (b) of FIG. 27, all these areexemplified as components included in the playback device PROD-D, butsome may be omitted.

In addition, the transmission unit PROD-D5 may transmit a moving imagethat has not be coded, and may transmit coded data which has been codedin a transmission coding scheme different from a recording codingscheme. In the latter case, a coding unit (not shown) that codes amoving image in the transmission coding scheme may be interposed betweenthe decoding unit PROD-D2 and the transmission unit PROD-D5.

Examples of the playback device PROD-D includes, for example, a DVDplayer, a BD player, a HDD player, and the like (in this case, theoutput terminal PROD-D4 connected to a television receiver or the likeis the main source of a moving image). Further, a television receiver(in this case, the display PROD-D3 is the main source of a movingimage), a digital signage (also referred to as a digital signage and anelectronic bulletin board, and the display PROD-D3 or the transmissionunit PROD-D5 are the main destination of a moving image), a desktop PC(in this case, the output terminal PROD-D4 or the transmission unitPROD-D5 is the main destination of a moving image), a laptop or tabletPC (in this case, the display PROD-D3 or the transmission unit PROD-D5is the main destination of a moving image), a smartphone (in this case,the display PROD-D3 or the transmission unit PROD-D5 is the maindestination of a moving image) are the examples of the playback devicePROD-D.

[Summary]

An image decoding device according to an aspect of the present inventionis an image decoding device which decodes hierarchically coded dataobtained by hierarchically coding image information regarding images ofdifferent qualities for respective layers, and restores an image of atarget layer to be decoded, the image decoding device includes

profile information decoding means (profile information decoding unit1221 a) for decoding profile information regarding the target layer fromthe coded data, in a case where a profile present flag indicates thatthe profile information regarding the target layer is to be presented,and configuring profile information regarding a predetermined decodedlayer to profile information regarding a target layer, in a case wherethe profile present flag indicates that profile information regarding atarget layer is not presented, in which the profile present flag(ProfilePresentFlag) indicates whether or not to present profileinformation indicating that coded data of the target layer can bedecoded by an image decoding device including which profile,

level information decoding means (level information decoding unit 1221b) for decoding level information indicating that the coded data of thetarget layer can be decoded by an image decoding device including whichlevel, from the coded data,

sublayer profile present flag decoding means (sublayer profile presentflag decoding unit 1221 c) for decoding a sublayer profile present flag(sub_layer_profile_flag) indicating whether or not to present sublayerprofile information regarding each sublayer included in the targetlayer, from the coded data,

sublayer level present flag decoding means (sublayer level present flagdecoding unit 1221 d) for decoding a sublayer level present flag(sub_layer_level_flag) indicating whether or not to present sublayerlevel information regarding each sublayer included in the target layer,from the coded data,

sublayer profile information decoding means (profile informationdecoding unit 1221 a) for decoding the sublayer profile informationregarding each sublayer included in the target layer, in a case whereafter the decoding of the sublayer profile present flag regarding eachsublayer, the sublayer profile present flag indicates that the sublayerprofile information is presented, and configuring the profileinformation regarding the target layer to the sublayer profileinformation regarding the sublayer in a case where the sublayer profilepresent flag indicates that the sublayer profile information is notpresented, and

sublayer level information decoding means (level information decodingunit 1221 b) for decoding the sublayer level information regarding eachsublayer included in the target layer, in a case where after thedecoding of the sublayer level present flag regarding each sublayer, thesublayer level present flag indicates that the sublayer levelinformation is presented, and configuring the level informationregarding the target layer to the sublayer level information regardingthe sublayer in a case where the sublayer level present flag indicatesthat the sublayer level information is not presented.

According to the above configuration, after decoding the sublayerprofile present flag and/or the sublayer level present flag regardingeach sublayer, the sublayer profile information and/or sublayer levelinformation are decoded or configured.

In other words, according to the configuration, the sublayer profilepresent flag and the sublayer level present flag corresponding to eachsublayer, and the sublayer profile information and the sublayer levelinformation corresponding to each sublayer are separately decoded.

Therefore, it is possible to easily specify an offset per bit untildecoding start points of sublayer profile information and sublayer levelinformation regarding a specific sublayer, based on a value of thesublayer profile present flag, a symbol amount of the sublayer profileinformation, a value of the sublayer level present flag, and a symbolamount of the sublayer level information.

Accordingly, there is an effect of reducing a processing amount requiredfor decoding the sublayer profile information and the sublayer levelinformation.

The image decoding device according to an aspect of the presentinvention may further include a byte-aligned data decoding means(byte-aligned data decoding unit 1221 e) for decoding byte-aligned datauntil the decoding start position is located in a byte boundary, fromthe coded data, after decoding the sublayer profile present flag and thesublayer level present flag.

According to the configuration, the sublayer profile present flag andthe sublayer level present flag corresponding to each sublayer, and thesublayer profile information and the sublayer level informationcorresponding to each sublayer are separately decoded, and byte-aligneddata which is inserted for byte alignment between both (between thesublayer profile present flag and the sublayer level present flag, andthe sublayer profile information and the sublayer level information) isfurther decoded.

Accordingly, as compared to the related art, it is possible toperforming decoding in a state where all syntax of the profile/levelinformation is byte-aligned. Therefore, it is possible to reduce thenumber of times of memory access regarding reading when decoding thesublayer profile present flag, the sublayer level present flag, thesublayer profile information, and the sublayer level information. Inother words, there is an effect of reducing a processing amount requiredfor decoding the profile/level information.

In the image decoding device according to an aspect of the presentinvention, when the profile present flag indicates that the profileinformation is presented, the sublayer profile present flag decodingmeans may decode the sublayer profile present flag from the coded data,and when the profile present flag indicates that the profile informationis not presented, the sublayer profile present flag decoding means mayset a value indicating not to present sublayer profile information inthe sublayer profile present flag.

According to the configuration, when profile present flag indicates thatthe profile information is not presented, it is estimated that thesublayer profile present flag of the sublayer is not presented, and thesublayer profile present flag is not explicitly decoded, such that ascompared to the related art, there is an effect of reducing a processingamount for decoding the sublayer profile present flag.

In the image decoding device according to an aspect of the presentinvention, when the profile present flag indicates that the profileinformation is presented, the byte-aligned data decoding means maydecode the byte-aligned data until the decoding start position islocated in the byte boundary, from the coded data, after decoding thesublayer profile present flag.

According to the configuration, when the sublayer profile present flagand the sublayer level present flag corresponding to the sublayer areseparately decoded and the profile present flag indicates that theprofile information is presented, the byte-aligned data which isinserted for byte alignment therebetween is further decoded.Accordingly, as compared to the related art, it is possible toperforming decoding in a state where all syntax of the profile/levelinformation is byte-aligned. Therefore, it is possible to reduce thenumber of times of memory access regarding reading when decoding thesublayer profile present flag, the sublayer level present flag, thesublayer profile information, and the sublayer level information. Inother words, there is an effect of reducing a processing amount requiredfor decoding the profile/level information.

In the image decoding device according to an aspect of the presentinvention, when the profile present flag indicates that the profileinformation is presented, the profile information decoding means maydecode at least, a profile space, a profile identifier, and profilecompatibility information as the profile information, and the levelinformation decoding means may decode a level identifier and a tier flagas the level information, without being dependent on the value of theprofile present flag.

According to the configuration, it is possible to decode the levelidentifier and the tier flag without being dependent on the profilepresent flag. Therefore, as compared to the related art, even when theprofile present flag indicates that the profile information is notpresented, there is an effect of acquiring a constraint of a leveldetermined by the level identifier and the tier flag, and of easilyspecifying whether a decoder is able to decode the coded data of thetarget layer.

In the image decoding device according to an aspect of the presentinvention, when the profile present flag indicates that the profileinformation is presented and the sublayer profile present flag indicatesthat the sublayer profile information is presented, the sublayer profileinformation decoding means may decode at least a sublayer profile space,a sublayer profile identifier, and sublayer profile compatibilityinformation as the sublayer profile information, and the sublayer levelinformation decoding means may decode a sublayer level identifier and asublayer tier flag as the sublayer level information without beingdependent on the value of the sublayer profile present flag.

According to the configuration, it is possible to decode the sublayerlevel identifier and the sublayer tier flag without being dependent onthe profile present flag and the sublayer profile present flag.Therefore, as compared to the related art, even when the profile presentflag or the sublayer profile present flag indicates that the profileinformation regarding the sublayer is not presented, there is an effectof acquiring a constraint of a level determined by the sublayer levelidentifier and the sublayer tier flag, with respect to the sublayer, andof easily specifying whether a decoder is able to decode the coded dataof the sublayer included in the target layer.

The image decoding device according to an aspect of the presentinvention further includes constraint flag decoding means for decoding aconstraint flag indicating whether or not to apply a profile constraint,a level constraint, or a tier constraint from the coded data,

when the constraint flag indicates that the profile constraint isapplied,

the profile information decoding means may

-   -   determine that a profile of a highest layer included in the        target layer and a profile of the target layer is the same, and    -   determine that a profile of each sublayer is configured to be        equal to or greater than a profile of a lower sublayer on which        the highest sublayer is dependent during decoding,

when the constraint flag indicates that the level constraint is applied,

the level information decoding means may

-   -   determine that a level of the highest layer included in the        target layer and a level of the target layer is the same, and    -   determine that a level of each sublayer is set to be equal to or        greater than a level of a lower sublayer on which the highest        sublayer is dependent during decoding, and

when the constraint flag indicates that the tier constraint is applied,

the level information decoding means may

-   -   determine that a tier of the highest layer included in the        target layer and a tier of the target layer is the same, and    -   determine that a tier of each sublayer is set to be equal to or        greater than a tier of a lower sublayer on which the highest        sublayer is dependent during decoding.

According to the above configuration, the image decoding device caneasily determine whether the profile, the level, and the tier of eachsublayer belonging to the target sublayer and the profile, the level,and the tier of a higher sublayer are coded data which isdiscontinuously generated without compatibility, before decoding theprofile information/level information. Further, there is an effect ofpreventing the generation of coded data in which the profile/level/tiernot compatible with the profile, the level, and the tier of the highersublayer are discontinuously set, by configuring whether or not to applythe profile constraint, the level constraint, and the tier constraintbetween the image decoding device and the image coding device. Further,since it is possible to suppress the profile, the level, and the tier towhich the image decoding device corresponds, to necessary minimumvalues, there is an effect of reducing the complexity of the imagedecoding device.

An image decoding device according to an aspect of the present inventionis an image decoding device which decodes hierarchically coded dataobtained by hierarchically coding image information regarding images ofdifferent qualities for respective layers, and restores an image of atarget layer to be decoded, the image decoding device includes

profile information decoding means (profile information decoding unit1221 a) for decoding profile information regarding the target layer fromthe coded data, in a case where a profile level present flag(ProfileLevelPresentFlag) indicates that profile information and levelinformation regarding the target layer are presented, and configuringprofile information regarding a predetermined decoded layer to theprofile information regarding the target layer, in a case where theprofile level present flag indicates that the profile information andthe level information regarding the target layer are not presented, inwhich the profile level present flag indicates whether or not to presentthe profile information and the level information respectivelyindicating that the coded data of the target layer can be decoded by animage decoding device including which profile and which level,

level information decoding means (level information decoding unit 1221b) for decoding level information regarding the target layer from thecoded data, in a case where the profile level present flag indicatesthat the profile information and the level information regarding thetarget layer are presented, and configuring level information regardinga predetermined decoded layer to the level information regarding thetarget layer, in a case where the profile level present flag indicatesthat the profile information and the level information regarding thetarget layer are not presented,

sublayer profile level present flag decoding means for decoding asublayer profile level present flag indicating whether or not to presentsublayer profile information and sublayer level information regardingeach sublayer included in the target layer,

sublayer profile information decoding means (profile informationdecoding unit 1221 a) for decoding the sublayer profile informationregarding each sublayer included in the target layer, in a case wherethe sublayer profile level present flag indicates that the sublayerprofile information and the sublayer level information are presented,and configuring the profile information regarding the target layer tothe sublayer profile information regarding the sublayer, in a case wherethe sublayer profile level present flag indicates that the sublayerprofile information and the sublayer level information are notpresented, and

sublayer level information decoding means (level information decodingunit 1221 b) for decoding the sublayer level information regarding eachsublayer included in the target layer, in a case where the sublayerprofile level present flag indicates that the sublayer profileinformation and the sublayer level information are presented, andconfiguring the level information regarding the target layer to thesublayer level information regarding the sublayer, in a case where thesublayer profile level present flag indicates that the sublayer profileinformation and the sublayer level information are not presented.

According to the above configuration, when the profile and the level arein common in a plurality of layers, it is possible to omit presentingthe profile information and the level information regarding the targetlayer. In other words, when the profile level present flag indicatesthat the profile information and the level information are notpresented, since the profile information and the level informationregarding a predetermined layer which is decoded is configured to theprofile information and the level information regarding the targetlayer, and the profile information and the level information are notexplicitly decoded, as compared to the related art, there is an effectof reducing a processing amount for decoding the profile information andthe level information regarding the target layer.

Further, when the profile and the level of the target layer and thesublayer profile and the sublayer level of the sublayer included in thetarget layer are common, it is possible to omit presenting the sublayerprofile information and the sublayer level information regarding thesublayer. In other words, when the sublayer profile level present flagindicates that the sublayer profile information and the sublayer levelinformation are not presented, since the profile information and thelevel information regarding the target layer which is decoded isconfigured to the sublayer profile information and the sublayer levelinformation regarding the target sublayer, and the sublayer profileinformation and the sublayer level information are not explicitlydecoded, as compared to the related art, there is an effect of reducinga processing amount for decoding the sublayer profile information andthe sublayer level information.

In addition, the image decoding device may include byte-aligned datadecoding means for decoding the byte-aligned data until the decodingstart position is located in the byte boundary, from the coded data,after decoding the sublayer profile level present flag.

According to the configuration, as compared to the related art, it ispossible to performing decoding in a state where all syntax of theprofile/level information is byte-aligned. Therefore, it is possible toreduce the number of times of memory access regarding reading whendecoding the sublayer profile present flag, the sublayer level presentflag, the sublayer profile information, and the sublayer levelinformation. In other words, there is an effect of reducing a processingamount required for decoding the profile/level information.

The image coding device that is configured as described above belongs tothe scope of the present invention, and also in this case, it ispossible to obtain the same effects as in the image decoding device.

Further, a data structure of hierarchically coded data that is generatedin the image coding device and decoded in the image decoding device alsobelongs to the scope of the present invention.

(Hardware Realization and Software Realization)

Finally, respective blocks of the hierarchical moving image decodingdevice 1 and the hierarchical moving image coding device 2 may beimplemented in hardware by a logic circuit formed on an integratedcircuit (IC chip), or may be implemented in software using a centralprocessing unit (CPU).

In the latter case, the respective devices include a CPU that executesinstructions of a control program for realizing each function, a readonly memory (ROM) that stores the program, a random access memory (RAM)that deploys the program, and a memory (recording medium) that storesthe program and various data. Then, the object of the present object maybe realized by supplying a recording medium in which recording programcodes of the control programs of the respective devices, which aresoftware for realizing the functions described above (an executableprogram, an intermediate code program, and a source program), arerecorded in a readable manner by the computer, to the respectivedevices, and by the computer (or a CPU or a micro processing unit (MPU))reading and executing the program codes which are recorded on therecording medium.

As the recording medium, for example, tapes such as a magnetic tape or acassette tape, disks including magnetic disk such as a floppy(registered trademark) disk/a hard disk, or an optical disk such as acompact disc read-only memory (CD-ROM)/a magneto-optical (MO)/a minidisc (MD)/a digital versatile disk (DVD)/a CD recordable (CD-R), cardssuch as an IC card (including a memory card)/an optical card,semiconductor memories such as a mask ROM/an erasable programmableread-only memory (EPROM)/an electrically erasable and programmableread-only memory (EEPROM (registered trademark))/a flash ROM, or logiccircuits such as a programmable logic device (PLD) and a fieldprogrammable gate array (FPGA) can be used.

Further, the respective devices are configuration to be connected to acommunication network, and the program codes may be supplied over thecommunications network. As long as any communication network is capableof transmitting the program codes, it is not particularly limited. Forexample, an inter-network, an intra-network, an extranet, a local areanetwork (LAN), an integrated services digital network (ISDN), avalue-added network (VAN), a community antenna television (CATV)communication network, a virtual private network, a telephone network, amobile communication network, a satellite communication network and thelike are available. Further, transmission media constituting thecommunication networks may be any medium capable of transmitting theprogram codes, and there is no restriction in a specific configurationor a type. For example, a wired medium such as the institute ofelectrical and electronic engineers (IEEE) 1394, a USB, a power-linecarrier, a cable TV line, a telephone line, and an asymmetric digitalsubscriber line (ADSL) line, or a wireless medium such as an infraredray such as an infrared data association (IrDA) or a remote control,Bluetooth (registered trademark), IEEE802.11 wireless, high data rate(HDR), near field communication (NFC), digital living network alliance(DLNA, registered trademark), a mobile telephone network, a satelliteconnection, a terrestrial digital network are available. In addition,the present invention may be realized in the form of a computer datasignal embedded in a carrier wave, in which the program codes areembodied by electronic transmission.

The present invention is not limited to the examples described above,various variations are possible in the scope of claims, and examplesobtained by appropriately combining technical means disclosed in theexamples are also included in the technical scope of the presentinvention.

(Supplementary note)

At least the following inventions are described in the presentspecification.

<1>

An image decoding device which decodes hierarchically coded dataobtained by hierarchically coding image information regarding images ofdifferent qualities for respective layers, and restores an image of atarget layer to be decoded, the image decoding device comprising:

profile information decoding means for decoding, from the coded data,profile information regarding the target layer, in a case where aprofile present flag (ProfilePresentFlag) indicating whether or not topresent profile information indicating that coded data of the targetlayer can be decoded by an image decoding device including which profileindicates that the profile information regarding the target layer ispresented, and configuring profile information regarding a predetermineddecoded layer to the profile information regarding the target layer, ina case where the profile present flag indicates that the profileinformation regarding the target layer is not presented;

level information decoding means for decoding, from the coded data,level information indicating that the coded data of the target layer canbe decoded by an image decoding device including which level;

sublayer profile present flag decoding means for decoding, from thecoded data, a sublayer profile present flag (sub_layer_profile_flag)indicating whether or not to present sublayer profile informationregarding each sublayer included in the target layer;

sublayer level present flag decoding means for decoding, from the codeddata, a sublayer level present flag (sub_layer_level_flag) indicatingwhether or not to present sublayer level information regarding eachsublayer included in the target layer;

sublayer profile information decoding means for decoding the sublayerprofile information regarding each sublayer included in the targetlayer, in a case where after the decoding of the sublayer profilepresent flag regarding each sublayer, the sublayer profile present flagindicates that the sublayer profile information is presented, andconfiguring the profile information regarding the target layer to thesublayer profile information regarding the sublayer in a case where thesublayer profile present flag indicates that the sublayer profileinformation is not presented; and

sublayer level information decoding means for decoding the sublayerlevel information regarding each sublayer included in the target layer,in a case where after the decoding of the sublayer level present flagregarding each sublayer, the sublayer level present flag indicates thatthe sublayer level information is presented, and configuring the levelinformation regarding the target layer to the sublayer level informationregarding the sublayer in a case where the sublayer level present flagindicates that the sublayer level information is not presented.

<2>

The image decoding device according to <1>, further comprising: abyte-aligned data decoding means for decoding, from the coded data,byte-aligned data until the decoding start position is located in a byteboundary, after decoding the sublayer profile present flag and thesublayer level present flag.

<3>

The image decoding device according to <1> or <2>, wherein in a casewhere the profile present flag indicates that the profile information ispresented, the sublayer profile present flag decoding unit decodes thesublayer profile present flag from the coded data, and in a case wherethe profile present flag indicates that the profile information is notpresented, the sublayer profile present flag decoding unit sets a valueindicating not to present sublayer profile information in the sublayerprofile present flag.

<4>

The image decoding device according to <2>, wherein in a case where theprofile present flag indicates that the profile information ispresented, the byte-aligned data decoding unit decodes, from the codeddata, the byte-aligned data until the decoding start position is locatedin the byte boundary, after decoding the sublayer profile present flag.

<5>

The image decoding device according to <1> or <2>, wherein in a casewhere the profile present flag indicates that the profile information ispresented, the profile information decoding unit decodes at least, aprofile space, a profile identifier, and profile compatibilityinformation as the profile information, and

the level information decoding unit decodes a level identifier and atier flag as the level information, without being dependent on the valueof the profile present flag.

<6>

The image decoding device according to <5>, wherein in a case where theprofile present flag indicates that the profile information is presentedand the sublayer profile present flag indicates that the sublayerprofile information is presented, the sublayer profile informationdecoding unit decodes at least a sublayer profile space, a sublayerprofile identifier, and sublayer profile compatibility information asthe sublayer profile information, and

the sublayer level information decoding unit decodes a sublayer levelidentifier and a sublayer tier flag as the sublayer level informationwithout being dependent on the value of the sublayer profile presentflag.

<7>

The image decoding device according to <1>, further comprisingconstraint flag decoding means for decoding, from the coded data, aconstraint flag indicating whether or not to apply a profile constraint,a level constraint, or a tier constraint,

wherein in a case where the constraint flag indicates to apply theprofile constraint,

the profile information decoding unit

-   -   determines that a profile of a highest sublayer included in the        target layer and a profile of the target layer are the same, and    -   determines that a profile of each sublayer is configured to be        equal to or greater than a profile of a lower sublayer on which        the highest sublayer is dependent during decoding,

in a case where the constraint flag indicates to apply the levelconstraint,

the level information decoding unit

-   -   determines that a level of the highest layer included in the        target layer and a level of the target layer are the same, and    -   determines that a level of each sublayer is set to be equal to        or greater than a level of a lower sublayer on which the highest        sublayer is dependent during decoding, and

in a case where the constraint flag indicates to apply the tierconstraint,

the level information decoding unit

-   -   determines that a tier of the highest layer included in the        target layer and a tier of the target layer are the same, and    -   determines that a tier of each sublayer is set to be equal to or        greater than a tier of a lower sublayer on which the highest        sublayer is dependent during decoding.

<8>

An image decoding device which decodes hierarchically coded dataobtained by hierarchically coding image information regarding images ofdifferent qualities for respective layers, and restores an image of atarget layer to be decoded, the image decoding device comprising:

profile information decoding means for decoding, from the coded data,profile information regarding the target layer, in a case where aprofile level present flag (ProfileLevelPresentFlag) indicates whetheror not to present the profile information and the level informationrespectively indicating that the coded data of the target layer can bedecoded by an image decoding device including which profile and whichlevel indicates that profile information and level information regardingthe target layer are presented, and configuring profile informationregarding a predetermined decoded layer to the profile informationregarding the target layer, in a case where the profile level presentflag indicates that the profile information and the level informationregarding the target layer are not presented;

level information decoding means for decoding, from the coded data,level information regarding the target layer, in a case where theprofile level present flag indicates that the profile information andthe level information regarding the target layer are presented, andconfiguring level information regarding a predetermined decoded layer tothe level information regarding the target layer, in a case where theprofile level present flag indicates that the profile information andthe level information regarding the target layer are not presented;

sublayer profile level present flag decoding means for decoding, formthe coded data, a sublayer profile level present flag indicating whetheror not to present sublayer profile information and sublayer levelinformation regarding each sublayer included in the target layer;

sublayer profile information decoding means for decoding the sublayerprofile information regarding each sublayer included in the targetlayer, in a case where the sublayer profile level present flag indicatesthat the sublayer profile information and the sublayer level informationare presented, and configuring the profile information regarding thetarget layer to the sublayer profile information regarding the sublayer,in a case where the sublayer profile level present flag indicates thatthe sublayer profile information and the sublayer level information arenot presented; and

sublayer level information decoding means for decoding the sublayerlevel information regarding each sublayer included in the target layer,in a case where the sublayer profile level present flag indicates thatthe sublayer profile information and the sublayer level information arepresented, and configuring the level information regarding the targetlayer to the sublayer level information regarding the sublayer, in acase where the sublayer profile level present flag indicates that thesublayer profile information and the sublayer level information are notpresented.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a hierarchical moving imagedecoding device that decodes coded data in which image data ishierarchically coded, and a hierarchical moving image coding device thatgenerates coded data in which image data is hierarchically coded.Further, the present invention is suitably applicable to a datastructure of the hierarchically coded data which is generated by thehierarchical moving image coding device and is referred to by thehierarchical moving image decoding device.

REFERENCE SIGNS LIST

-   -   1: HIERARCHICAL MOVING IMAGE DECODING DEVICE (IMAGE DECODING        DEVICE)    -   11: NAL DEMULTIPLEXING UNIT    -   12: VARIABLE LENGTH DECODING UNIT    -   121: HEADER INFORMATION DECODING UNIT    -   1211: PROFILE/LEVEL INFORMATION DECODING UNIT    -   1221 a: PROFILE INFORMATION DECODING UNIT    -   1221 b: LEVEL INFORMATION DECODING UNIT    -   1221 c: SUBLAYER PROFILE PRESENT FLAG DECODING UNIT    -   1221 d: SUBLAYER LEVEL PRESENT FLAG DECODING UNIT    -   1221 e: BYTE-ALIGNED DATA DECODING UNIT    -   1221 f: SUBLAYER PROFILE LEVEL PRESENT FLAG DECODING UNIT    -   122: PREDICTION INFORMATION DECODING UNIT    -   123: TRANSFORM COEFFICIENT INFORMATION DECODING UNIT    -   14: PREDICTION PARAMETER RESTORATION UNIT    -   15: TEXTURE RESTORATION UNIT    -   16: BASE DECODING UNIT    -   2: HIERARCHICAL MOVING IMAGE CODING DEVICE (IMAGE CODING DEVICE)    -   21: PREDICTION PARAMETER DETERMINATION UNIT    -   22: VARIABLE-LENGTH CODING UNIT    -   221: HEADER INFORMATION CODING UNIT    -   2211: PROFILE/LEVEL INFORMATION CODING UNIT    -   2221 a: PROFILE INFORMATION CODING UNIT    -   2221 b: LEVEL INFORMATION CODING UNIT    -   2221 c: SUBLAYER PROFILE PRESENT FLAG CODING UNIT    -   2221 d: SUBLAYER LEVEL PRESENT FLAG CODING UNIT    -   2221 e: BYTE-ALIGNED DATA CODING UNIT    -   2221 f: SUBLAYER PROFILE LEVEL PRESENT FLAG CODING UNIT    -   222: PREDICTION INFORMATION CODING UNIT    -   223: TRANSFORM COEFFICIENT INFORMATION CODING UNIT    -   23: BASE DECODING UNIT    -   24: TEXTURE INFORMATION GENERATION UNIT    -   25: PREDICTION INFORMATION GENERATION UNIT    -   26: NAL MULTIPLEXING UNIT

The invention claimed is:
 1. An image decoding device which decodescoded data obtained by coding image information, the image decodingdevice comprising: a processor; and a memory connected to the processor;wherein the processor receives a video parameter set, the processordecodes information for expansion, having a code length of 16 bits, inthe video parameter set, and thereafter receives profile/levelinformation included in the video parameter set, the processor decodessublayer profile present flags, included in the profile/levelinformation, indicating the presence or absence of sublayer profileinformation regarding respective sublayer, the processor decodessublayer level present flags, included in the profile/level information,indicating the presence or absence of sublayer level informationregarding the respective sublayers, and, the processor decodesbyte-aligned data, included in the profile/level information, determinedbased on the number of the sublayers, and the processor decodes thesublayer profile information, included in the profile/level information,a first bit of the profile/level information is byte-aligned by theinformation for expansion, and a first bit of the sublayer profileinformation is byte-aligned by the byte-aligned data.